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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] The sum of first two Lychrel numbers is prime, i.e., 196+295. [Loungrides] It is conjectured that 491 is the smallest prime not of the form x^{3} + y^{3} + 2z^{3}. [Wesolowski]
(There are 4 curios for this number that have not yet been approved by an editor.)
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