21755456 has 28 divisors (see below), whose sum is σ = 45445680. Its totient is φ = 10304640.

The previous prime is 21755429. The next prime is 21755471. The reversal of 21755456 is 65455712.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7730 + ... + 10161.

It is an arithmetic number, because the mean of its divisors is an integer number (1623060).

Almost surely, 2^21755456 is an apocalyptic number.

It is an amenable number.

21755456 is an abundant number, since it is smaller than the sum of its proper divisors (23690224).

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

21755456 is a wasteful number, since it uses less digits than its factorization.

21755456 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17922 (or 17912 counting only the distinct ones).

The product of its digits is 42000, while the sum is 35.

The square root of 21755456 is about 4664.2744344646. The cubic root of 21755456 is about 279.1618473166.

The spelling of 21755456 in words is "twenty-one million, seven hundred fifty-five thousand, four hundred fifty-six".