21256788 has 36 divisors (see below), whose sum is σ = 57698592. Its totient is φ = 6073200.

The previous prime is 21256777. The next prime is 21256799. The reversal of 21256788 is 88765212.

It is an interprime number because it is at equal distance from previous prime (21256777) and next prime (21256799).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 17488 + ... + 18663.

Almost surely, 2^21256788 is an apocalyptic number.

21256788 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21256788 is an abundant number, since it is smaller than the sum of its proper divisors (36441804).

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

21256788 is a wasteful number, since it uses less digits than its factorization.

21256788 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36172 (or 36163 counting only the distinct ones).

The product of its digits is 53760, while the sum is 39.

The square root of 21256788 is about 4610.5084318327. The cubic root of 21256788 is about 277.0124024040.

The spelling of 21256788 in words is "twenty-one million, two hundred fifty-six thousand, seven hundred eighty-eight".