The new number, expressed as 2 to the 20,996,011th power minus 1, has 6,320,430 decimal digits and was discovered November 17th. It is more than two million digits larger than the previous largest known prime number, and belongs to a special class of rare prime numbers called Mersenne primes . The discovery marks only the 40th known Mersenne prime, named after Marin Mersenne , a 17th century French monk who first studied the numbers 300 years ago.

Mersenne primes are most relevant to number theory, but most participants join GIMPS simply for the fun of having a role in real research and the chance of finding a new Mersenne prime. The new prime is 63% of the qualifying size for the $100,000 Electronic Frontier Foundation award for the first 10-million-digit prime, also being sought by the project's volunteers. In May 2000, a previous participant won the foundation's $50,000 award for discovering the first million-digit prime.

Michael Shafer, a chemical engineering graduate student at Michigan State University, used a 2 GHz Pentium 4 Dell Dimension PC running for 19 days to prove the number prime. Now in its eighth year, GIMPS has accomplished what no other distributed computing project has: six consecutive successes.

Entropia founder, Scott Kurowski developed the PrimeNet system that runs GIMPS using his company's technology to demonstrate its scalability and power with a demanding distributed search application. PrimeNet pulls together hundreds of thousands of computers in parallel to create a virtual supercomputer running at 9 trillion calculations per second, or 'teraflops'. This enabled GIMPS to find the prime in just two years instead of the 25,000 years a single PC would have required.

The new prime was independently verified by Guillermo Ballester Valor of Granada, Spain using twelve days of time on a 1.4GHz quad Itanium II server at the HP Test Drive center, and by Ernst Mayer of Cupertino, California using three weeks of time on a 1 GHz HP Alpha workstation. The discovery is the sixth record prime found by the GIMPS project, and the fourth discovered using distributed computing software from Entropia Inc. In recognition of every GIMPS contributor's effort, credit for this new discovery will go to "Shafer, Woltman, Kurowski, et al".

"There are more primes out there", invited GIMPS founder George Woltman, "and anyone with an Internet-connected computer can participate." The calculations work by using spare background time that would otherwise be wasted.

The mathematical algorithm George Woltman uses for GIMPS, called the IBDWT (irrational-base discrete weighted transform), was discovered by Apple Distinguished Scientist, Dr. Richard Crandall, director of the Center for Advanced Computation at Reed College, Portland, Oregon. The IBDWT and related algorithms are available in the book, "Prime Numbers: A Computational Perspective", by R. Crandall and C. Pomerance.

All the necessary software can be downloaded for free at