15
This number is a composite.
Just showing those entries submitted by 'Capelle': (Click here to show all)
15 is the smallest number which is product of two distinct odd primes. [Capelle]
The only known natural number n > 0 such that the sum of the five known Fermat primes raised to the power n is prime. Curiously, it is the product of the first two Fermat primes. [Capelle]
The number of supersingular primes, i.e., primes that divide the order of the Monster group (an algebraic construction with 246 * 320 * 59 * 76 * 112 * 133 * 17 * 19 * 23 * 29 * 31 * 41 * 47 * 59 * 71 elements). [Capelle]
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