21663630 has 24 divisors (see below), whose sum is σ = 56325672. Its totient is φ = 5776944.

The previous prime is 21663623. The next prime is 21663647. The reversal of 21663630 is 3636612.

21663630 is a `hidden beast` number, since 21 + 6 + 6 + 3 + 630 = 666.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21663594 and 21663603.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 120264 + ... + 120443.

It is an arithmetic number, because the mean of its divisors is an integer number (2346903).

Almost surely, 2^21663630 is an apocalyptic number.

21663630 is an abundant number, since it is smaller than the sum of its proper divisors (34662042).

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

21663630 is a wasteful number, since it uses less digits than its factorization.

21663630 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 240720 (or 240717 counting only the distinct ones).

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

The square root of 21663630 is about 4654.4204795012. The cubic root of 21663630 is about 278.7685288681.

The spelling of 21663630 in words is "twenty-one million, six hundred sixty-three thousand, six hundred thirty".