21408944 has 20 divisors (see below), whose sum is σ = 41559840. Its totient is φ = 10683840.

The previous prime is 21408943. The next prime is 21408949. The reversal of 21408944 is 44980412.

It is a self number, because there is not a number n which added to its sum of digits gives 21408944.

It is not an unprimeable number, because it can be changed into a prime (21408943) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 10574 + ... + 12434.

It is an arithmetic number, because the mean of its divisors is an integer number (2077992).

Almost surely, 2^21408944 is an apocalyptic number.

It is an amenable number.

21408944 is a deficient number, since it is larger than the sum of its proper divisors (20150896).

21408944 is a wasteful number, since it uses less digits than its factorization.

21408944 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2588 (or 2582 counting only the distinct ones).

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

The square root of 21408944 is about 4626.9800086017. The cubic root of 21408944 is about 277.6717828246.

The spelling of 21408944 in words is "twenty-one million, four hundred eight thousand, nine hundred forty-four".