21555522 has 24 divisors (see below), whose sum is σ = 46906860. Its totient is φ = 7153920.

The previous prime is 21555511. The next prime is 21555539. The reversal of 21555522 is 22555512.

It can be written as a sum of positive squares in 2 ways, for example, as 21538881 + 16641 = 4641^2 + 129^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1854 + ... + 6822.

Almost surely, 2^21555522 is an apocalyptic number.

21555522 is an abundant number, since it is smaller than the sum of its proper divisors (25351338).

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

21555522 is a wasteful number, since it uses less digits than its factorization.

21555522 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5218 (or 5215 counting only the distinct ones).

The product of its digits is 5000, while the sum is 27.

The square root of 21555522 is about 4642.7924786706. The cubic root of 21555522 is about 278.3040425589.

The spelling of 21555522 in words is "twenty-one million, five hundred fifty-five thousand, five hundred twenty-two".