21944556 has 18 divisors (see below), whose sum is σ = 55471052. Its totient is φ = 7314840.

The previous prime is 21944551. The next prime is 21944579. The reversal of 21944556 is 65544912.

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 609571 = 21944556 / (2 + 1 + 9 + 4 + 4 + 5 + 5 + 6).

It is a self number, because there is not a number n which added to its sum of digits gives 21944556.

It is not an unprimeable number, because it can be changed into a prime (21944551) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 304750 + ... + 304821.

Almost surely, 2^21944556 is an apocalyptic number.

It is an amenable number.

21944556 is an abundant number, since it is smaller than the sum of its proper divisors (33526496).

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

21944556 is a wasteful number, since it uses less digits than its factorization.

21944556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 609581 (or 609576 counting only the distinct ones).

The product of its digits is 43200, while the sum is 36.

The square root of 21944556 is about 4684.5016810756. The cubic root of 21944556 is about 279.9683467620.

It can be divided in two parts, 21944 and 556, that added together give a square (22500 = 150²).

The spelling of 21944556 in words is "twenty-one million, nine hundred forty-four thousand, five hundred fifty-six".