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jdewerd | 1 year ago

The 50 000 000th prime is 982451653, but fun fact: you may have already memorized a prime much larger than this without even realizing you have done so!

2^255-19

This is where Curve 25519 and the associated cryptography (ed25519, x25519) gets its name from. Written out, 2^255-19=57896044618658097711785492504343953926634992332820282019728792003956564819949.

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lifthrasiir|1 year ago

You could have memorized even large one if you are familiar with the full name of the Mersenne Twister PRNG: MT19937 is named so because its period is 2^19937-1 which is a prime number (in fact, the largest known one at the time of Zigler's writing). In my knowledge any larger prime number hasn't been used for the practical purpose.

jdewerd|1 year ago

Cool, I hadn't run into it before so thanks for introducing me!

I was going to include the digits for comparison, but yes, on second thought 6002 digits is probably too much for polite inclusion in a HN post.

ape4|1 year ago

On a Linux command line:

    echo '2^255-19' | bc