61

This number is a prime.

61 is the smallest proper prime, i.e., a prime p which ends in the digit 1 in decimal and whose reciprocal in base-10 has a repeating sequence of length p-1, where each digit (0, 1, ..., 9) appears in the repeating sequence the same number of times, as does each other digit (namely, (p-1)/10 times). [Dickson]