18221401656 has 64 divisors (see below), whose sum is σ = 51239930400. Its totient is φ = 6073794720.

The previous prime is 18221401651. The next prime is 18221401663. The reversal of 18221401656 is 65610412281.

It is a happy number.

18221401656 is a `hidden beast` number, since 182 + 21 + 401 + 6 + 56 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 18221401656.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18221401651) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 503235 + ... + 538226.

Almost surely, 2^18221401656 is an apocalyptic number.

It is an amenable number.

18221401656 is an abundant number, since it is smaller than the sum of its proper divisors (33018528744).

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

18221401656 is an equidigital number, since it uses as much as digits as its factorization.

18221401656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1041488 (or 1041466 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 36.

The spelling of 18221401656 in words is "eighteen billion, two hundred twenty-one million, four hundred one thousand, six hundred fifty-six".