21664082 has 12 divisors (see below), whose sum is σ = 35719278. Its totient is φ = 9847200.

The previous prime is 21664081. The next prime is 21664109. The reversal of 21664082 is 28046612.

It can be written as a sum of positive squares in only one way, i.e., 21242881 + 421201 = 4609^2 + 649^2 .

It is a hoax number, since the sum of its digits (29) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21664081) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 44519 + ... + 45002.

Almost surely, 2^21664082 is an apocalyptic number.

21664082 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21664082 is a deficient number, since it is larger than the sum of its proper divisors (14055196).

21664082 is a wasteful number, since it uses less digits than its factorization.

21664082 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 89545 (or 89534 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 29.

The square root of 21664082 is about 4654.4690352391. The cubic root of 21664082 is about 278.7704676398.

The spelling of 21664082 in words is "twenty-one million, six hundred sixty-four thousand, eighty-two".