21256136 has 32 divisors (see below), whose sum is σ = 45770400. Its totient is φ = 9152640.

The previous prime is 21256129. The next prime is 21256153. The reversal of 21256136 is 63165212.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4685 + ... + 8028.

It is an arithmetic number, because the mean of its divisors is an integer number (1430325).

Almost surely, 2^21256136 is an apocalyptic number.

It is an amenable number.

21256136 is an abundant number, since it is smaller than the sum of its proper divisors (24514264).

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

21256136 is a wasteful number, since it uses less digits than its factorization.

21256136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12749 (or 12745 counting only the distinct ones).

The product of its digits is 2160, while the sum is 26.

The square root of 21256136 is about 4610.4377232536. The cubic root of 21256136 is about 277.0095701490.

The spelling of 21256136 in words is "twenty-one million, two hundred fifty-six thousand, one hundred thirty-six".