21664674 has 24 divisors (see below), whose sum is σ = 49411440. Its totient is φ = 6841368.

The previous prime is 21664667. The next prime is 21664703. The reversal of 21664674 is 47646612.

21664674 is a `hidden beast` number, since 2 + 1 + 6 + 646 + 7 + 4 = 666.

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 11 ways as a sum of consecutive naturals, for example, 31332 + ... + 32015.

It is an arithmetic number, because the mean of its divisors is an integer number (2058810).

Almost surely, 2^21664674 is an apocalyptic number.

21664674 is an abundant number, since it is smaller than the sum of its proper divisors (27746766).

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

21664674 is a wasteful number, since it uses less digits than its factorization.

21664674 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63374 (or 63371 counting only the distinct ones).

The product of its digits is 48384, while the sum is 36.

The square root of 21664674 is about 4654.5326295988. The cubic root of 21664674 is about 278.7730068753.

The spelling of 21664674 in words is "twenty-one million, six hundred sixty-four thousand, six hundred seventy-four".