# The Largest Prime Number Ever Known Is 23 Million Digits Long

## Just trust the mathematical masterminds on this one.

pixeldreams.eu/ShutterstockHow many prime numbers can you list off the top of your head? No matter how fast you count, we’re willing to bet you can’t even come close to the largest prime number ever known. Don’t beat yourself up, though; counting that high would be a nearly impossible feat.

Why, you ask? This is the highest number anyone has counted to, for one. And second, the new largest prime number in the world is 23 million digits long. Yes, really!

While the number is far too large to list here, it goes by many names. Number nerds call it 2 to the 77,232,917th power – 1, for short. Others use the nickname M77232917. If you’re interested in seeing a longer version, it looks a little something like this:

467333183359231099988335585561115521251321102817714495798582338593567923480521177207484311099740208849621368090038049317…

(23,249,185 digits later)

…285376004518786055402223376672925679282131965467343395945397370476369279894627999939614659217371136582730618069762179071

Unless you’re a mathematical mastermind, we could all benefit from one quick reminder: A prime number is only divisible by 1 and itself. For instance, 7 and 11 are prime—which has something to do with the scientific reason why 7 is probably your favorite number.

John Pace, a FedEx employee from Tennessee, discovered the new prime. He belongs to an online group called the Great Internet Mersenne Prime Search (GIMPS), in which thousands of volunteers run software on their personal computers to find the next largest prime number. And while this prime is the biggest we’ve found so far, even larger ones exist; we just haven’t discovered them yet.

Aside from being just plain cool, these huge numbers could someday be used in fields like cryptography, Internet security, and computing. “When they ultimately get to quantum computers, however long that takes, they’ll be able to crack current encryption in milliseconds,” Pace told NPR. “So there’s going to be a need for extremely large prime numbers, and I’d like to at least have left some legacy that I’ve helped contribute something to society.”

If your mind isn’t boggled already, we’ve got some more brain food for you: The longest word in the English language is 189,819 letters long.

[Source: NPR, Slate]