Mathematician Discovers Largest Known Prime Number With 22 Million Digits By Charissa Echavez | Jan 21, 2016 06:50 AM EST Great Internet Mersenne Prime Search (GIMPS) has just discovered the largest prime number known yet. It is longer than the previously recorded prime number by up to 5 million digits. Prime numbers are numbers more than one that can only be divided by one and itself. Because it is so hard to find large primes, smaller ones like 2, 3, 5 and 7 are the most commonly known. Dubbed as the M74207281, the latest prime number discovered has an eye-popping 22,338,618 digits. Dr. Cooper was able to obtain it by multiplying 74,207,281 twos and then subtracting one after, that is, 2^74,207,281-1. The latest discovery by Dr Curtis Cooper from the University of Central Missouri is under a special class category called Mersenne prime. Derived from the French monk Marin Mersenne who devoted his time to study these numbers over three centuries ago, hence its named after him. Mersenne primes are usually obtained by multiplying a number of twos and deducting one. Currently, there are only 49 Mersenne primes, including M74207281. Seeing mathematicians' interest for prime number, people tend to ask "what's in it for us?" Prime numbers are particularly essential for cryptanalysis. Primes ensures secured online transactions such as banking, chatting and shopping. Although hundred-digit long primes are usually used and those that reach millions seem too big for practical value, Mersenne primes are actually used as a test for computer hardware. "One prime project discovered that there was a problem in some computer processors that only showed up in certain circumstances," University College London's cyber security expert Dr. Steven Murdoch said. Since 1996, GIMPS has already uncovered 15 Mersenne primes. For anyone interested in digging primes, download Prime95 on their personal computers for free. Anyone who can decode new prime numbers can receive a reward of up to $50,000.