21656912 has 20 divisors (see below), whose sum is σ = 44429076. Its totient is φ = 10191360.

The previous prime is 21656911. The next prime is 21656923. The reversal of 21656912 is 21965612.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 10394176 + 11262736 = 3224^2 + 3356^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21656911) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 39539 + ... + 40082.

Almost surely, 2^21656912 is an apocalyptic number.

It is an amenable number.

21656912 is an abundant number, since it is smaller than the sum of its proper divisors (22772164).

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

21656912 is a wasteful number, since it uses less digits than its factorization.

21656912 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79646 (or 79640 counting only the distinct ones).

The product of its digits is 6480, while the sum is 32.

The square root of 21656912 is about 4653.6987440100. The cubic root of 21656912 is about 278.7397100507.

The spelling of 21656912 in words is "twenty-one million, six hundred fifty-six thousand, nine hundred twelve".