21655712 has 24 divisors (see below), whose sum is σ = 45915156. Its totient is φ = 9994752.

The previous prime is 21655709. The next prime is 21655723. The reversal of 21655712 is 21755612.

It can be written as a sum of positive squares in 2 ways, for example, as 21492496 + 163216 = 4636^2 + 404^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25613 + ... + 26444.

Almost surely, 2^21655712 is an apocalyptic number.

It is an amenable number.

21655712 is an abundant number, since it is smaller than the sum of its proper divisors (24259444).

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

21655712 is a wasteful number, since it uses less digits than its factorization.

21655712 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52080 (or 52072 counting only the distinct ones).

The product of its digits is 4200, while the sum is 29.

The square root of 21655712 is about 4653.5698125203. The cubic root of 21655712 is about 278.7345616739.

The spelling of 21655712 in words is "twenty-one million, six hundred fifty-five thousand, seven hundred twelve".