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What is the largest prime number that has been discovered?

The largest known prime is very large, running to the hundreds if not thousands of digits. New largest primes get discovered every few years. I believe there was a good review article in _Scientific American_ a few years ago. Check their index. Also, I think this question may have been asked before. Did you check the math archive?


If you have access to a Web browser, check out URL This page is maintained by Chris Caldwell of the Department of Mathematics, University of Tennessee - Martin. According to this page, the largest known prime is 2^859433-1. - 1 , which has 258,716 (yikes!) digits. Its primality was announced on Jan. 4, 1994 by David Slowinski, who with Paul Gage proved (using a Cray C90 supercomputer) that it was prime.


Hmmm, just looked at my answer and noted I'd managed to mistype the prime number. I meant to type 2^859433 - 1 . The "^", by the way, means "to the power of", so for example 2^3 means 2*2*2.

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