21656313 has 24 divisors (see below), whose sum is σ = 35974848. Its totient is φ = 12297312.

The previous prime is 21656311. The next prime is 21656347. The reversal of 21656313 is 31365612.

21656313 is a `hidden beast` number, since 2 + 1 + 656 + 3 + 1 + 3 = 666.

It is not a de Polignac number, because 21656313 - 2¹ = 21656311 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21656311) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9906 + ... + 11892.

It is an arithmetic number, because the mean of its divisors is an integer number (1498952).

Almost surely, 2^21656313 is an apocalyptic number.

It is an amenable number.

21656313 is a deficient number, since it is larger than the sum of its proper divisors (14318535).

21656313 is a wasteful number, since it uses less digits than its factorization.

21656313 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2173 (or 2170 counting only the distinct ones).

The product of its digits is 3240, while the sum is 27.

The square root of 21656313 is about 4653.6343861545. The cubic root of 21656313 is about 278.7371401764.

The spelling of 21656313 in words is "twenty-one million, six hundred fifty-six thousand, three hundred thirteen".