The book is now available! 491
(another Prime Pages' Curiosity)
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The nth Prime Page will now find any of the first 2.623˙1015 primes or π(x) for x up to 1017.

+ The smallest irregular prime having an irregularity index of 3. [Noe]

+ 491 is a Sophie Germain prime. 491 is also a divisor of a Generalized Fermat Number, as 491 * (2^123281+1) divides GF(123280,10) = 10^(2^123280) + 1. [Carmichael]

+ It is conjectured that 491 is the smallest prime not of the form x3 + y3 + 2z3. [Wesolowski]

(There are 4 curios for this number that have not yet been approved by an editor.)

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