21973864 has 16 divisors (see below), whose sum is σ = 44946720. Its totient is φ = 9988080.

The previous prime is 21973849. The next prime is 21973871. The reversal of 21973864 is 46837912.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 124764 + ... + 124939.

It is an arithmetic number, because the mean of its divisors is an integer number (2809170).

Almost surely, 2^21973864 is an apocalyptic number.

It is an amenable number.

21973864 is an abundant number, since it is smaller than the sum of its proper divisors (22972856).

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

21973864 is a wasteful number, since it uses less digits than its factorization.

21973864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 249720 (or 249716 counting only the distinct ones).

The product of its digits is 72576, while the sum is 40.

The square root of 21973864 is about 4687.6288248964. The cubic root of 21973864 is about 280.0929283386.

The spelling of 21973864 in words is "twenty-one million, nine hundred seventy-three thousand, eight hundred sixty-four".