GIMPS crack whip on plucky processor to find largest prime number

23 million-digit figure revealed after six days of non-stop calculations

The Great Internet Mersenne Prime Search (GIMPS) has announced the discovery of a new largest Mersenne prime number, 2^77,232,917 -1.

The figure, viewable here (.zip file), was found by GIMPS' network of volunteer prime hunters, and is the 50th Mersenne prime discovered. It comprises 23,249,425 digits, and is 910,807 digits longer than the previous largest Mersenne Prime, 2^74,207,281 -1.

The machine that made the discovery belongs to electrical engineer Jonathan Pace of Tennessee. After six days of continuous computing with a quad-core Intel i5-6600 processor, the new prime was found on December 26.

The official credit for the discovery is shared by three others in recognition of their involvement. These are George Woltman, who founded GIMPS and developed the Prime95 software Pace used to calculate the number, and Scott Kurowski and Aaron Blosser, who worked on PrimeNet, the system GIMPS uses to coordinate the computers of their volunteers.

The number was subsequently verified by four different methods on five different sets of hardware, with operators Aaron Blosser, David Stanfill, Andreas Höglund and Ernst Mayer taking secondary credit for the find.

The last Mersenne prime was also discovered by GIMPS in January 2016, with the effort led by Dr Curtis Cooper of the University of Central Missouri. GIMPS has found the last 15 largest Mersenne primes since the project was set up in 1996.

Mersenne primes, named after the French friar and mathematician Marin Mersenne, are based on the formula 2^x -1. The discovery of prime numbers in general, numbers only divisible by one and themselves, was for centuries undertaken by mathematicians for sheer enjoyment, but has since been put to practical use in cryptography. ®