21891256 has 16 divisors (see below), whose sum is σ = 41095800. Its totient is φ = 10932384.

The previous prime is 21891227. The next prime is 21891269. The reversal of 21891256 is 65219812.

It is a congruent number.

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, 11766 + ... + 13498.

Almost surely, 2^21891256 is an apocalyptic number.

It is an amenable number.

21891256 is a deficient number, since it is larger than the sum of its proper divisors (19204544).

21891256 is a wasteful number, since it uses less digits than its factorization.

21891256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3318 (or 3314 counting only the distinct ones).

The product of its digits is 8640, while the sum is 34.

The square root of 21891256 is about 4678.8092502260. The cubic root of 21891256 is about 279.7414961092.

The spelling of 21891256 in words is "twenty-one million, eight hundred ninety-one thousand, two hundred fifty-six".