666635904 has 192 divisors, whose sum is σ = 2161486080. Its totient is φ = 195379200.

The previous prime is 666635903. The next prime is 666635939. The reversal of 666635904 is 409536666.

It is a tau number, because it is divible by the number of its divisors (192).

It is a self number, because there is not a number n which added to its sum of digits gives 666635904.

It is not an unprimeable number, because it can be changed into a prime (666635903) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 391984 + ... + 393680.

It is an arithmetic number, because the mean of its divisors is an integer number (11257740).

Almost surely, 2^666635904 is an apocalyptic number.

666635904 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 666635904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1080743040).

666635904 is an abundant number, since it is smaller than the sum of its proper divisors (1494850176).

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

666635904 is a wasteful number, since it uses less digits than its factorization.

666635904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1759 (or 1744 counting only the distinct ones).

The product of its (nonzero) digits is 699840, while the sum is 45.

The square root of 666635904 is about 25819.2932513653. The cubic root of 666635904 is about 873.5670276973.

The spelling of 666635904 in words is "six hundred sixty-six million, six hundred thirty-five thousand, nine hundred four".