###### February 6, 2013

# Largest Known Prime Number Discovered Using Crowd-Sourcing

**April Flowers for redOrbit.com - Your Universe Online **

The largest known prime number was recently discovered on the computer of Curtis Cooper, a Great Internet Mersenne Prime Search (GIMPS) volunteer. The new number is 2 raised to^{ 57,885,161} power minus 1 (or 2 multiplied by itself 57,855,161 times minus one) and it has 17,425,170 digits. The GIMPS project is the second longest continuously-running "grassroots supercomputing" project in Internet history, with 360,000 CPU's peaking at 150 trillion calculations per second.

Dr. Cooper and the University of Central Missouri are the largest individual contributors to the GIMPS project, and their latest find makes them eligible for a $3,000 GIMPS research discovery award.

Mersenne primes numbers like the one just discovered are a special class of extremely rare prime numbers. This is only the 48th known Mersenne prime ever discovered. The increasingly difficult to find numbers were named for the French monk Marin Mersenne who studied these types of numbers more than 350 years ago.

Founded in 1996, the GIMPS project has already discovered all 14 of the largest known Mersenne primes using a crowd-sourcing technique. To search for the primes, volunteers download and use a free program. The organization also offers cash awards ranging from $3,000 to $50,000 to anyone lucky enough to compute a new prime.

To verify that the prime discovery process was error free, three individuals — Serge Batalov, Jerry Hallett, and Dr. Jeff Gilchrist — independently verified the new number using different programs running on different hardware. Batalov ran Ernst Mayer's MLucas software on a 32-core server in 6 days to verify the new prime, while Jerry Hallett verified the prime using the CUDALucas software running on a NVidia GPU in 3.6 days. Finally, Dr. Jeff Gilchrist verified the find twice using the GIMPS software on an Intel i7 CPU in 4.5 days and the CUDALucas program on a NVidia GTX 560 Ti in 7.7 days.

The official credit for the discovery will go to "C. Cooper, G. Woltman, S.Kurowski, et al." The GIMPS project´s next operational goal is to win the Electronic Frontier Foundation (EFF) award of $150,000 for the discovery of a 100 million-digit prime number.