The Great Internet Mersenne Prime Search (GIMPS) is a collaborative project of volunteers who use freely available software to search for Mersenne prime numbers. The project was founded by George Woltman, who also wrote the software Prime95 and MPrime for the project. Scott Kurowski wrote the Internet PrimeNet Server that supports the research to demonstrate […]
The Great Internet Mersenne Prime Search (GIMPS) is a collaborative project of volunteers who use freely available software to search for Mersenne prime numbers. The project was founded by George Woltman, who also wrote the software Prime95 and MPrime for the project. Scott Kurowski wrote the Internet PrimeNet Server that supports the research to demonstrate Entropiadistributed computing software, a company he founded in 1997. GIMPS is registered as Mersenne Research, Inc. Kurowski is Executive Vice President and board director of Mersenne Research Inc. GIMPS is said to be one of the first large scale distributed computing projects over the Internet for research purposes.^{[1]}
The project has found a total of fourteen Mersenne primes as of 5 February 2013, eleven of which were the largest known prime number at their respective times of discovery. The largest known prime as of January 2013 is 2^{57,885,161} ? 1 (or M_{57,885,161} in short). This prime was discovered on January 25, 2013 by Curtis Cooper at the University of Central Missouri.^{[2]}
To perform its testing, the project relies primarily on Édouard Lucas and Derrick Henry Lehmer‘s primality test,^{[3]} an algorithm that is both specialized to testing Mersenne primes and particularly efficient on binary computer architectures. They also have a less expensive trial division phase, taking hours instead of weeks, used to rapidly eliminate Mersenne numbers with small factors, which make up a large proportion of candidates. John Pollard’s p ? 1 algorithm is also used to search for larger factors.
On January 25th, prolific GIMPS contributor Dr. Curtis Cooper discovered the 48th known Mersenne prime, 2^{57,885,161}1, a 17,425,170 digit number. This find shatters the previous record prime number of 12,978,189 digits, also a GIMPS prime, discovered over 4 years ago. The discovery is eligible for a $3,000 GIMPS research discovery award.
Dr. Cooper is a professor at the University of Central Missouri. This is the third record prime for Dr. Cooper and his University. Their first record prime was discovered in 2005, eclipsed by their second record in 2006. Computers at UCLA broke that record in 2008. UCLA held the record until Dr. Cooper and the University of Central Missouri reclaimed the world record with this discovery.
While Dr. Cooper’s computer found the record prime, the discovery would not have been possible without all the GIMPS volunteers that sifted through numerous nonprime candidates. GIMPS founder George Woltman and PrimeNet creator Scott Kurowski thank and congratulate all the GIMPS members that made this discovery possible.
Mersenne primes are extremely rare, only 48 are known. GIMPS, founded in 1996, has discovered the last 14 Mersenne primes. Mersenne primes were named for the French monk Marin Mersenne, who studied these numbers more than 350 years ago. Chris Caldwell maintains an authoritative web site on the history of Mersenne primes as well as the largest known primes.
The primality proof took 39 days of nonstop computing on one of the University of Central Missouri’s PCs. To establish there were no errors during the proof, the new prime was independently verified using different programs running on different hardware. Jerry Hallett verified the prime using CUDALucas running on a NVidia GPU in 3.6 days. Dr. Jeff Gilchrist verified the find using the standard GIMPS software on an Intel i7 CPU in 4.5 days. Finally, Serge Batalov ran Ernst Mayer’s MLucas software on a 32core server in 6 days (resource donated by Novartis IT group) to verify the new prime.
You can read a little more in the short press release.
Start the program! (Linux and FreeBSD users should run the program from the command line with a m switch, i.e. “./mprime m”). Enter your optional userID created on the website in Step 1, and optionally name your computer. We recommend Windows users select Options, Start at Bootup or Start at Logon. 


That’s all you need to do! The program contacts a central server called PrimeNet to get some work to do. Usually the program and PrimeNet know the best work to assign, but it’s up to you!You can administer your account and computers on your userID’s account page. Once you complete a workunit you can track your standings on the competitive stats pages the server updates every hour (see Top Producers in the menu, left, for more stats). You can monitor each of your computers’ progress, even remotecontrol the work assignments they request using your userID’s CPUs page!
Linux and FreeBSD versions can also be set up to run every time you restart your computer. Ask for help at the Mersenne Forum. 
Questions and Problems: Please consult the readme.txt file for possible answers. You can also search for an answer, or ask for help in the GIMPS forums. Otherwise, you will need to address your question to one of the two people who wrote the program. Networking and server problems should be sent to Scott Kurowski. Such problems include errors contacting the server, problems with assignments or userids, and errors on the server’s statistics page. All other problems and questions should be sent to George Woltman, but please consult the forums first.
Disclaimers: See GIMPS Terms and Conditions. However, please do send bug reports and suggestions for improvements.
Software Source CodeIf you use GIMPS source code to find Mersenne primes, you must agree to adhere to the GIMPS free software license agreement. Other than that restriction, you may use this code as you see fit.
The source code for the program is highly optimized Intel assembly language. There are many morereadable FFT algorithms available on the web and in textbooks. The program is also completely nonportable. If you are curious anyway, you can download all the source code (40.6MB). This file includes all the version 27.9 source code for Windows, Linux, FreeBSD, and Mac OS X. Last updated: December 12, 2012.
The GIMPS program is very loosely based on C code written by Richard Crandall. Luke Welsh has started a web page that points to Richard Crandall’s program and other available source code that you can use to help search for Mersenne primes.
Other available freewareAt this time, Ernst Mayer’s Mlucas program and Guillermo Ballester Valor’s Glucas program are the best choices for nonIntel architectures. Luke Welsh has a web page that points to available source code of mostly historical interest you can use to help search for Mersenne primes.