21493856 has 24 divisors (see below), whose sum is σ = 42797160. Its totient is φ = 10624768.

The previous prime is 21493853. The next prime is 21493867. The reversal of 21493856 is 65839412.

It is a happy number.

It is a zygodrome in base 9.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21493853) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 926 + ... + 6621.

It is an arithmetic number, because the mean of its divisors is an integer number (1783215).

Almost surely, 2^21493856 is an apocalyptic number.

It is an amenable number.

21493856 is a deficient number, since it is larger than the sum of its proper divisors (21303304).

21493856 is an equidigital number, since it uses as much as digits as its factorization.

21493856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7646 (or 7638 counting only the distinct ones).

The product of its digits is 51840, while the sum is 38.

The square root of 21493856 is about 4636.1466758505. The cubic root of 21493856 is about 278.0383985053.

The spelling of 21493856 in words is "twenty-one million, four hundred ninety-three thousand, eight hundred fifty-six".