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421

This number is a prime.

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The product of first 421 positive even numbers minus 1 (i.e., 2^421*421!-1) is the smallest titanic prime of form 2^p*p!-1, where p is a prime. [Loungrides]

Submitted: 2016-06-16 11:29:03; Last Modified: 2018-12-28 22:15:12.