21808264 has 8 divisors (see below), whose sum is σ = 40890510. Its totient is φ = 10904128.

The previous prime is 21808247. The next prime is 21808271. The reversal of 21808264 is 46280812.

It can be written as a sum of positive squares in only one way, i.e., 21548164 + 260100 = 4642^2 + 510^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1363009 + ... + 1363024.

Almost surely, 2^21808264 is an apocalyptic number.

It is an amenable number.

21808264 is a deficient number, since it is larger than the sum of its proper divisors (19082246).

21808264 is a wasteful number, since it uses less digits than its factorization.

21808264 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2726039 (or 2726035 counting only the distinct ones).

The product of its (nonzero) digits is 6144, while the sum is 31.

The square root of 21808264 is about 4669.9319052851. The cubic root of 21808264 is about 279.3875388540.

The spelling of 21808264 in words is "twenty-one million, eight hundred eight thousand, two hundred sixty-four".