21666532 has 12 divisors (see below), whose sum is σ = 38841516. Its totient is φ = 10568960.

The previous prime is 21666493. The next prime is 21666553. The reversal of 21666532 is 23566612.

It can be written as a sum of positive squares in 2 ways, for example, as 2359296 + 19307236 = 1536^2 + 4394^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21666494 and 21666503.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65893 + ... + 66220.

It is an arithmetic number, because the mean of its divisors is an integer number (3236793).

Almost surely, 2^21666532 is an apocalyptic number.

It is an amenable number.

21666532 is a deficient number, since it is larger than the sum of its proper divisors (17174984).

21666532 is a wasteful number, since it uses less digits than its factorization.

21666532 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132158 (or 132156 counting only the distinct ones).

The product of its digits is 12960, while the sum is 31.

The square root of 21666532 is about 4654.7322157134. The cubic root of 21666532 is about 278.7809759996.

The spelling of 21666532 in words is "twenty-one million, six hundred sixty-six thousand, five hundred thirty-two".