21640896 has 42 divisors (see below), whose sum is σ = 62031372. Its totient is φ = 7213440.

The previous prime is 21640891. The next prime is 21640919. The reversal of 21640896 is 69804612.

21640896 is a `hidden beast` number, since 2 + 1 + 640 + 8 + 9 + 6 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 21640896.

It is not an unprimeable number, because it can be changed into a prime (21640891) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 18210 + ... + 19361.

Almost surely, 2^21640896 is an apocalyptic number.

It is an amenable number.

21640896 is an abundant number, since it is smaller than the sum of its proper divisors (40390476).

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

21640896 is a wasteful number, since it uses less digits than its factorization.

21640896 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37589 (or 37576 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The square root of 21640896 is about 4651.9776439704. The cubic root of 21640896 is about 278.6709807054.

The spelling of 21640896 in words is "twenty-one million, six hundred forty thousand, eight hundred ninety-six".