21633666 has 32 divisors (see below), whose sum is σ = 45988800. Its totient is φ = 6765120.

The previous prime is 21633653. The next prime is 21633671. The reversal of 21633666 is 66633612.

It is a happy number.

It is a nude number because it is divisible by every one of its digits.

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, 11556 + ... + 13296.

It is an arithmetic number, because the mean of its divisors is an integer number (1437150).

Almost surely, 2^21633666 is an apocalyptic number.

21633666 is an abundant number, since it is smaller than the sum of its proper divisors (24355134).

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

21633666 is a wasteful number, since it uses less digits than its factorization.

21633666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1874.

The product of its digits is 23328, while the sum is 33.

The square root of 21633666 is about 4651.2004901961. The cubic root of 21633666 is about 278.6399435493.

The spelling of 21633666 in words is "twenty-one million, six hundred thirty-three thousand, six hundred sixty-six".