666840728 has 16 divisors (see below), whose sum is σ = 1280822760. Its totient is φ = 325288000.

The previous prime is 666840673. The next prime is 666840731. The reversal of 666840728 is 827048666.

It is a congruent number.

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, 1016198 + ... + 1016853.

Almost surely, 2^666840728 is an apocalyptic number.

It is an amenable number.

666840728 is a deficient number, since it is larger than the sum of its proper divisors (613982032).

666840728 is a wasteful number, since it uses less digits than its factorization.

666840728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2033098 (or 2033094 counting only the distinct ones).

The product of its (nonzero) digits is 774144, while the sum is 47.

The square root of 666840728 is about 25823.2594379563. The cubic root of 666840728 is about 873.6564864107.

The spelling of 666840728 in words is "six hundred sixty-six million, eight hundred forty thousand, seven hundred twenty-eight".