21656036 has 12 divisors (see below), whose sum is σ = 38822700. Its totient is φ = 10563840.

The previous prime is 21656023. The next prime is 21656039. The reversal of 21656036 is 63065612.

It can be written as a sum of positive squares in 2 ways, for example, as 6100900 + 15555136 = 2470^2 + 3944^2 .

It is not an unprimeable number, because it can be changed into a prime (21656039) 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, 65861 + ... + 66188.

It is an arithmetic number, because the mean of its divisors is an integer number (3235225).

Almost surely, 2^21656036 is an apocalyptic number.

It is an amenable number.

21656036 is a deficient number, since it is larger than the sum of its proper divisors (17166664).

21656036 is a wasteful number, since it uses less digits than its factorization.

21656036 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132094 (or 132092 counting only the distinct ones).

The product of its (nonzero) digits is 6480, while the sum is 29.

The square root of 21656036 is about 4653.6046243745. The cubic root of 21656036 is about 278.7359517544.

The spelling of 21656036 in words is "twenty-one million, six hundred fifty-six thousand, thirty-six".