0015

The eighth composite number and the sixth semiprime and the first odd and fourth discrete semiprime; its proper divisors are 1, 3, and 5, so the first of the form (3.q),where q is a higher prime. a deficient number, a lucky number, a bell number (i.e., the number of partitions for a set of size 4), a pentatope number, [5] and a repdigit in binary (1111) and quaternary (33). In hexadecimal, and higher bases, it is represented as F.