21630636 has 36 divisors (see below), whose sum is σ = 56565600. Its totient is φ = 6961248.

The previous prime is 21630629. The next prime is 21630659. The reversal of 21630636 is 63603612.

21630636 is a `hidden beast` number, since 21 + 6 + 3 + 0 + 636 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9316 + ... + 11403.

Almost surely, 2^21630636 is an apocalyptic number.

It is an amenable number.

21630636 is an abundant number, since it is smaller than the sum of its proper divisors (34934964).

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

21630636 is a wasteful number, since it uses less digits than its factorization.

21630636 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20758 (or 20753 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 27.

The square root of 21630636 is about 4650.8747564302. The cubic root of 21630636 is about 278.6269342201.

The spelling of 21630636 in words is "twenty-one million, six hundred thirty thousand, six hundred thirty-six".