583

583 = 11 x 53.

583 is the sum of the first 27 nonprimes (A051349).

583 is the first integer n such that 47 x 2ⁿ + 1 is prime.

583 is the least integer that is not a sum or difference of two integers such that all their prime factors are 2, 3, and 5.

583 is the smallest number whose reciprocal has period 26.

583 is the sum of six positive fifth powers: 583 = 3⁵ + 3⁵ + 2⁵ + 2⁵ + 2⁵ + 1⁵.

Source: Prime Curios!