21644772 has 24 divisors (see below), whose sum is σ = 50580096. Its totient is φ = 7204128.

The previous prime is 21644747. The next prime is 21644801. The reversal of 21644772 is 27744612.

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, 13813 + ... + 15299.

It is an arithmetic number, because the mean of its divisors is an integer number (2107504).

Almost surely, 2^21644772 is an apocalyptic number.

It is an amenable number.

21644772 is an abundant number, since it is smaller than the sum of its proper divisors (28935324).

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

21644772 is a wasteful number, since it uses less digits than its factorization.

21644772 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2707 (or 2705 counting only the distinct ones).

The product of its digits is 18816, while the sum is 33.

The square root of 21644772 is about 4652.3942223333. The cubic root of 21644772 is about 278.6876168657.

The spelling of 21644772 in words is "twenty-one million, six hundred forty-four thousand, seven hundred seventy-two".