21054636 has 36 divisors (see below), whose sum is σ = 56353752. Its totient is φ = 6605184.

The previous prime is 21054617. The next prime is 21054643. The reversal of 21054636 is 63645012.

21054636 = 324² + 325² + ... + 459².

21054636 is a `hidden beast` number, since 21 + 0 + 5 + 4 + 636 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

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, 16590 + ... + 17813.

It is an arithmetic number, because the mean of its divisors is an integer number (1565382).

Almost surely, 2^21054636 is an apocalyptic number.

It is an amenable number.

21054636 is an abundant number, since it is smaller than the sum of its proper divisors (35299116).

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

21054636 is a wasteful number, since it uses less digits than its factorization.

21054636 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34430 (or 34425 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 27.

The square root of 21054636 is about 4588.5330989326. The cubic root of 21054636 is about 276.1314748531.

Subtracting from 21054636 its product of nonzero digits (4320), we obtain a triangular number (21050316 = T₆₄₈₈).

Adding to 21054636 its reverse (63645012), we get a palindrome (84699648).

The spelling of 21054636 in words is "twenty-one million, fifty-four thousand, six hundred thirty-six".