21888656 has 20 divisors (see below), whose sum is σ = 44904492. Its totient is φ = 10300416.

The previous prime is 21888653. The next prime is 21888667. The reversal of 21888656 is 65688812.

It can be written as a sum of positive squares in 2 ways, for example, as 15335056 + 6553600 = 3916^2 + 2560^2 .

It is a super-2 number, since 2×21888656² = 958226522972672, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21888653) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 39965 + ... + 40508.

Almost surely, 2^21888656 is an apocalyptic number.

It is an amenable number.

21888656 is an abundant number, since it is smaller than the sum of its proper divisors (23015836).

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

21888656 is a wasteful number, since it uses less digits than its factorization.

21888656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80498 (or 80492 counting only the distinct ones).

The product of its digits is 184320, while the sum is 44.

The square root of 21888656 is about 4678.5313935037. The cubic root of 21888656 is about 279.7304208092.

The spelling of 21888656 in words is "twenty-one million, eight hundred eighty-eight thousand, six hundred fifty-six".