(2 * 2521) - 1 = 712 and 2 * (2521 - 1) = 7!. [Forslund]
2521 minus one is the smallest EPORN.
25212 = 14563 - 14553, i.e., one solution to the Diophantine equation z2 = x3 - y3. A Diophantine equation is a polynomial equation in which only integer solutions are allowed. These are named after the Greek algebraist Diophantus who lived in the 3rd century. [Mizuki]
The smallest prime formed by concatenating consecutive
composite odd numbers. [Green]
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