66221428 has 24 divisors (see below), whose sum is σ = 142631552. Its totient is φ = 26197344.

The previous prime is 66221399. The next prime is 66221497. The reversal of 66221428 is 82412266.

It is a self number, because there is not a number n which added to its sum of digits gives 66221428.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 90600 + ... + 91327.

Almost surely, 2^66221428 is an apocalyptic number.

It is an amenable number.

66221428 is an abundant number, since it is smaller than the sum of its proper divisors (76410124).

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

66221428 is a wasteful number, since it uses less digits than its factorization.

66221428 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 181951 (or 181949 counting only the distinct ones).

The product of its digits is 9216, while the sum is 31.

The square root of 66221428 is about 8137.6549447614. The cubic root of 66221428 is about 404.5754388460.

The spelling of 66221428 in words is "sixty-six million, two hundred twenty-one thousand, four hundred twenty-eight".