The more prime numbers we find, the harder it gets to find a new one. The latest prime number, discovered using the free Great Internet Mersenne Prime Search (GIMPS) software, is 22,338,618 digits long, over five million digits longer than the last one discovered. The new prime, 274,207,281-1, is also only the 49th known Mersenne prime. The number is so large that a text file containing it occupies 22 MB.
As hardware geeks, we were immediately curious about the machines responsible for the discovery. For the initial proof, Dr. Curtis Cooper at the University of Central Missouri ran GIMPS on a PC running an Intel Core i7-4790 for 31 days straight. His proof was verified independently three times, first by CUDALucas software powered by Geforce GTX Titan Black GPUs running continuously for 2.3 days. A system running AMD Fury X GPUs accomplished the same feat in 3.5 days, as did a system employing two Amazon EC2 servers with 18-core Intel Xeon CPUs.
While primes are important in number theory and cryptography, Dr. Cooper's discovery may not have any immediate application because of its sheer size. The GIMPS software has produced valuable insights unrelated to discovering prime numbers, however. Just recently, mathematicians working with GIMPS uncovered a bug in Intel's Skylake processors.
Anyone interested in a shot at internet glory and a $3,000 discovery prize is welcome to join in the search for the 50th Mersenne prime. Who knows? With that kind of prize money, you just might be able to pay off the electricity bill you'll incur.