21668944 has 80 divisors (see below), whose sum is σ = 49175424. Its totient is φ = 9152000.

The previous prime is 21668929. The next prime is 21668957. The reversal of 21668944 is 44986612.

It is a junction number, because it is equal to n+sod(n) for n = 21668897 and 21668906.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 214494 + ... + 214594.

Almost surely, 2^21668944 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21668944, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24587712).

21668944 is an abundant number, since it is smaller than the sum of its proper divisors (27506480).

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

21668944 is a wasteful number, since it uses less digits than its factorization.

21668944 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 196 (or 190 counting only the distinct ones).

The product of its digits is 82944, while the sum is 40.

The square root of 21668944 is about 4654.9912996696. The cubic root of 21668944 is about 278.7913205987.

The spelling of 21668944 in words is "twenty-one million, six hundred sixty-eight thousand, nine hundred forty-four".