The computer of Dr. Curtis Cooper at the University of Central Missouri has made a rare mathematical discovery — the world’s largest known prime number, 257,885,161 - 1. The integer is more than 17 million digits long, so if you wanted a hard copy to hang on your wall or something it would take more than 13,000 pages of A4 paper. The size of the find crushes the 2009 discovery of 243,112,609 - 1, which fell just shy of the 13-million-digit mark.

The top 10 largest known primes are Mersennes uncovered by GIMPS

Cooper’s find is part of the Great Internet Mersenne Prime Search (GIMPS) —a distributed computing project that hunts down Mersenne primes. The numbers take the form 2p - 1, where p is also a prime number, although not all numbers that have the form are prime — hence the years of non-stop computation between discoveries. The New Scientist points out that all of the top 10 largest known primes are Mersennes uncovered by GIMPS.

So far, the world’s number crunchers have only turned up 48 Mersenne primes in all, although mathematicians conjecture that there might be an infinite number of them. In other words, there’s still a lot more searching to do. And that searching gets more and more time-consuming the further out we search. The check to ensure that Cooper’s prime was, in fact, not divisible by any rogue factors took 39 days of continuous work from one of the campus computers.