21291992 has 16 divisors (see below), whose sum is σ = 40215960. Its totient is φ = 10567744.

The previous prime is 21291971. The next prime is 21292013. The reversal of 21291992 is 29919212.

It is an interprime number because it is at equal distance from previous prime (21291971) and next prime (21292013).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8618 + ... + 10809.

Almost surely, 2^21291992 is an apocalyptic number.

It is an amenable number.

21291992 is a deficient number, since it is larger than the sum of its proper divisors (18923968).

21291992 is a wasteful number, since it uses less digits than its factorization.

21291992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19570 (or 19566 counting only the distinct ones).

The product of its digits is 5832, while the sum is 35.

The square root of 21291992 is about 4614.3246526442. The cubic root of 21291992 is about 277.1652408929.

The spelling of 21291992 in words is "twenty-one million, two hundred ninety-one thousand, nine hundred ninety-two".