666644428 has 48 divisors (see below), whose sum is σ = 1216051200. Its totient is φ = 319581504.

The previous prime is 666644413. The next prime is 666644449. The reversal of 666644428 is 824446666.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3349873 + ... + 3350071.

It is an arithmetic number, because the mean of its divisors is an integer number (25334400).

Almost surely, 2^666644428 is an apocalyptic number.

It is an amenable number.

666644428 is a deficient number, since it is larger than the sum of its proper divisors (549406772).

666644428 is a wasteful number, since it uses less digits than its factorization.

666644428 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 526 (or 524 counting only the distinct ones).

The product of its digits is 1327104, while the sum is 46.

The square root of 666644428 is about 25819.4583211964. The cubic root of 666644428 is about 873.5707509959.

The spelling of 666644428 in words is "six hundred sixty-six million, six hundred forty-four thousand, four hundred twenty-eight".