21660436 has 24 divisors (see below), whose sum is σ = 43527680. Its totient is φ = 9238752.

The previous prime is 21660421. The next prime is 21660449. The reversal of 21660436 is 63406612.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4510 + ... + 7978.

Almost surely, 2^21660436 is an apocalyptic number.

It is an amenable number.

21660436 is an abundant number, since it is smaller than the sum of its proper divisors (21867244).

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

21660436 is a wasteful number, since it uses less digits than its factorization.

21660436 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3703 (or 3701 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 28.

The square root of 21660436 is about 4654.0773521720. The cubic root of 21660436 is about 278.7548280180.

The spelling of 21660436 in words is "twenty-one million, six hundred sixty thousand, four hundred thirty-six".