21908444 has 48 divisors (see below), whose sum is σ = 44190720. Its totient is φ = 9434880.

The previous prime is 21908437. The next prime is 21908449. The reversal of 21908444 is 44480912.

It is a super-2 number, since 2×21908444² = 959959837002272, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21908444.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21908449) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 39779 + ... + 40325.

It is an arithmetic number, because the mean of its divisors is an integer number (920640).

Almost surely, 2^21908444 is an apocalyptic number.

It is an amenable number.

21908444 is an abundant number, since it is smaller than the sum of its proper divisors (22282276).

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

21908444 is a wasteful number, since it uses less digits than its factorization.

21908444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 618 (or 616 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 32.

The square root of 21908444 is about 4680.6456819546. The cubic root of 21908444 is about 279.8146903105.

The spelling of 21908444 in words is "twenty-one million, nine hundred eight thousand, four hundred forty-four".