21400864 has 24 divisors (see below), whose sum is σ = 42336000. Its totient is φ = 10648896.

The previous prime is 21400849. The next prime is 21400877. The reversal of 21400864 is 46800412.

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, 5637 + ... + 8635.

It is an arithmetic number, because the mean of its divisors is an integer number (1764000).

Almost surely, 2^21400864 is an apocalyptic number.

It is an amenable number.

21400864 is a deficient number, since it is larger than the sum of its proper divisors (20935136).

21400864 is a wasteful number, since it uses less digits than its factorization.

21400864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3232 (or 3224 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 25.

The square root of 21400864 is about 4626.1067864890. The cubic root of 21400864 is about 277.6368461751.

The spelling of 21400864 in words is "twenty-one million, four hundred thousand, eight hundred sixty-four".