GIMPS Finds a Prime!
21398269-1 is prime
(Another of the Prime Pages' resources)
 New record prime (GIMPS): 282,589,933-1 with 24,862,048 digits by P. Laroche, G. Woltman, A. Blosser, et al. (7 Dec 2018).

Search Site

The 5000
Top 20
How Many?

Prime Curios!
Prime Lists

e-mail list

Submit primes

This is no longer the largest known prime.
Click here for information on and new records.

How do you slay a giant? One way is to get a very big gun. Most of the previous record primes were found just that way--by the super-computers of their day armed with the Lucas-Lehmer test

Another way is to get together with several hundred friends and assault the giant as a team. Recently the GIMPS (Great Internet Mersenne Prime Search) project did just that! On 13 November 1996 Joel Armengaud discovered the new Mersenne prime 21398269-1. He did this by using George Woltman's free implementation of the Lucas-Lehmer test and by working together with over 700 other individuals scattered across the Internet. 

And what a giant they slew! This 420921 digit number (formed by multiplying two by itself 1398268 times, then subtracting one) is now the largest known prime. It is also the 35th known Mersenne prime, and so comes paired with the 35th known perfect number. There are still infinitely many more giants left to slay, so why not surf over to Woltman's GIMPS site and join the search for the next record prime? 

Lilliputians attack Gulliver  For more information click on one of the following: 

The Prime Pages
Another prime page by Chris K. Caldwell <>