21913856 has 18 divisors (see below), whose sum is σ = 43742622. Its totient is φ = 10956800.

The previous prime is 21913849. The next prime is 21913861. The reversal of 21913856 is 65831912.

It can be written as a sum of positive squares in only one way, i.e., 17977600 + 3936256 = 4240^2 + 1984^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 42545 + ... + 43056.

Almost surely, 2^21913856 is an apocalyptic number.

It is an amenable number.

21913856 is a deficient number, since it is larger than the sum of its proper divisors (21828766).

21913856 is an frugal number, since it uses more digits than its factorization.

21913856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85617 (or 85603 counting only the distinct ones).

The product of its digits is 12960, while the sum is 35.

The square root of 21913856 is about 4681.2237716221. The cubic root of 21913856 is about 279.8377291051.

The spelling of 21913856 in words is "twenty-one million, nine hundred thirteen thousand, eight hundred fifty-six".