21807936 has 42 divisors (see below), whose sum is σ = 62510162. Its totient is φ = 7269120.

The previous prime is 21807931. The next prime is 21807943. The reversal of 21807936 is 63970812.

It can be written as a sum of positive squares in only one way, i.e., 21678336 + 129600 = 4656^2 + 360^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 21807936.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21807931) 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, 18355 + ... + 19506.

Almost surely, 2^21807936 is an apocalyptic number.

It is an amenable number.

21807936 is an abundant number, since it is smaller than the sum of its proper divisors (40702226).

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

21807936 is a wasteful number, since it uses less digits than its factorization.

21807936 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37879 (or 37866 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 36.

The square root of 21807936 is about 4669.8967868680. The cubic root of 21807936 is about 279.3861381683.

The spelling of 21807936 in words is "twenty-one million, eight hundred seven thousand, nine hundred thirty-six".