21931902 has 24 divisors (see below), whose sum is σ = 47800584. Its totient is φ = 7267344.

The previous prime is 21931891. The next prime is 21931913. The reversal of 21931902 is 20913912.

It is an interprime number because it is at equal distance from previous prime (21931891) and next prime (21931913).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 408 + ... + 6635.

It is an arithmetic number, because the mean of its divisors is an integer number (1991691).

Almost surely, 2^21931902 is an apocalyptic number.

21931902 is an abundant number, since it is smaller than the sum of its proper divisors (25868682).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21931902 is a wasteful number, since it uses less digits than its factorization.

21931902 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7224 (or 7221 counting only the distinct ones).

The product of its (nonzero) digits is 972, while the sum is 27.

The square root of 21931902 is about 4683.1508624002. The cubic root of 21931902 is about 279.9145232285.

It can be divided in two parts, 2193 and 1902, that added together give a triangular number (4095 = T₉₀).

The spelling of 21931902 in words is "twenty-one million, nine hundred thirty-one thousand, nine hundred two".