21664426 has 32 divisors (see below), whose sum is σ = 39595392. Its totient is φ = 8678400.

The previous prime is 21664417. The next prime is 21664457. The reversal of 21664426 is 62446612.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 53826 + ... + 54226.

It is an arithmetic number, because the mean of its divisors is an integer number (1237356).

Almost surely, 2^21664426 is an apocalyptic number.

21664426 is a deficient number, since it is larger than the sum of its proper divisors (17930966).

21664426 is a wasteful number, since it uses less digits than its factorization.

21664426 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 654.

The product of its digits is 13824, while the sum is 31.

The square root of 21664426 is about 4654.5059888242. The cubic root of 21664426 is about 278.7719431471.

The spelling of 21664426 in words is "twenty-one million, six hundred sixty-four thousand, four hundred twenty-six".