646666404 has 24 divisors (see below), whose sum is σ = 1509361728. Its totient is φ = 215487840.

The previous prime is 646666399. The next prime is 646666439. The reversal of 646666404 is 404666646.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 44809 + ... + 57455.

It is an arithmetic number, because the mean of its divisors is an integer number (62890072).

Almost surely, 2^646666404 is an apocalyptic number.

It is an amenable number.

646666404 is an abundant number, since it is smaller than the sum of its proper divisors (862695324).

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

646666404 is a wasteful number, since it uses less digits than its factorization.

646666404 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16915 (or 16913 counting only the distinct ones).

The product of its (nonzero) digits is 497664, while the sum is 42.

The square root of 646666404 is about 25429.6363324370. The cubic root of 646666404 is about 864.7556992159.

The spelling of 646666404 in words is "six hundred forty-six million, six hundred sixty-six thousand, four hundred four".