Big Discovery: Largest Prime Number

The Great Internet Mersenne Prime Search just paid dividends in the hunt for ever-bigger prime numbers, the New Scientist reports. University of Central Missouri mathematician Curtis Cooper has discovered the biggest prime number yet, a 17 million-digit behemoth, as part of GIMPS. The project uses a huge network of volunteer computers as part of the search for Mersenne primes, a rare type of prime number first noted in the 17th century.

The number—2 raised to the power of 57,885,161 minus 1—is more than 4 million digits longer than the previous record holder, which was found in 2008, LiveScience adds. So what is the giant number good for? Large primes can be used for online encryption, but mathematicians say it's mostly about the thrill of the hunt. "People enjoy it for the challenge of the discovery of finding something that's never been known before," the computer scientist who created GIMPS says. Cooper also wins $3,000 for the discovery, but a bigger payday looms. The Electronic Frontier Foundation will award $150,000 to the person who finds a prime with 100 million digits; a one billion-digit find returns a $250,000 prize. (More prime number stories.)