21908472 has 16 divisors (see below), whose sum is σ = 54771240. Its totient is φ = 7302816.

The previous prime is 21908449. The next prime is 21908483. The reversal of 21908472 is 27480912.

It is a happy number.

It is a super-2 number, since 2×21908472² = 959962290749568, which contains 22 as substring.

It is a hoax number, since the sum of its digits (33) coincides with the sum of the digits of its distinct prime factors.

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, 456403 + ... + 456450.

Almost surely, 2^21908472 is an apocalyptic number.

It is an amenable number.

21908472 is an abundant number, since it is smaller than the sum of its proper divisors (32862768).

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

21908472 is a wasteful number, since it uses less digits than its factorization.

21908472 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 912862 (or 912858 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 33.

The square root of 21908472 is about 4680.6486729939. The cubic root of 21908472 is about 279.8148095158.

The spelling of 21908472 in words is "twenty-one million, nine hundred eight thousand, four hundred seventy-two".