On January 4, the Great Internet Mersenne Prime Search (GIMPS), a group of volunteers who use freely available software to search for Mersenne prime numbers, announced the discovery of a new “largest known prime number.” For those that need a refresher, a prime number is a positive integer that can only be divided by itself and 1. Since they follow no set pattern, the numbers are hard to discover, which is probably why mathematicians are continually challenging themselves to find the next big one.

The recent discovery comprises a staggering 23,249,425 million digits. According to GIMPS, the number is big enough to fill an entire shelf of books, totaling 9,000 pages. The team asserts “If every second you were to write five digits to an inch then 54 days later you’d have a number stretching over 73 miles (118 kilometers) long.”

Nicknamed M77232917 (because the prime number is 2^{77,232,917} − 1), it is the 50^{th} Mersenne prime and the 16^{th} discovered by GIMPS since the collaborative computer project began in 1996. The particular class of rare prime numbers is named after 17th-century French polymath Marin Mersenne, who came up with a way to derive prime numbers using a simple equation: 2^{n} – 1 (n being a prime number).

The discovery, which is larger than the previous record holder by almost a million digits, can be credited to Jonathan Pace. It took the FedEx engineer, who has been searching for big primes for 14 years, six days of non-stop computing to find M77232917. To test if his calculations were accurate, the number was independently confirmed by four different programs running on different hardware configurations.

Though the incessant quest for an increasingly large prime number may seem frivolous, they do come in handy for use in computer encryption to protect important data from hackers. But since the current software uses prime numbers that are hundreds of digits long, not millions, M77232917 will not be needed anytime soon. However, its discovery has earned Pace $3,000, and, more importantly, elevated his status among math lovers, at least until the next largest prime number is found. Given that the genius who uncovers a prime number with 100 million digits will get both fame and $150,000 from the Electronic Frontier Foundation, the competition to discover the next record-breaking prime number can only increase.

Resources: newscientist.com,bbc.co.uk, gizmondo.com