21885666 has 32 divisors (see below), whose sum is σ = 47996928. Its totient is φ = 6597840.

The previous prime is 21885653. The next prime is 21885671. The reversal of 21885666 is 66658812.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13975 + ... + 15461.

It is an arithmetic number, because the mean of its divisors is an integer number (1499904).

Almost surely, 2^21885666 is an apocalyptic number.

21885666 is an abundant number, since it is smaller than the sum of its proper divisors (26111262).

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

21885666 is a wasteful number, since it uses less digits than its factorization.

21885666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1726.

The product of its digits is 138240, while the sum is 42.

The square root of 21885666 is about 4678.2118378714. The cubic root of 21885666 is about 279.7176831298.

The spelling of 21885666 in words is "twenty-one million, eight hundred eighty-five thousand, six hundred sixty-six".