666778904 has 64 divisors (see below), whose sum is σ = 1418342400. Its totient is φ = 291088000.

The previous prime is 666778897. The next prime is 666778921. The reversal of 666778904 is 409877666.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 578729 + ... + 579879.

It is an arithmetic number, because the mean of its divisors is an integer number (22161600).

Almost surely, 2^666778904 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 666778904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (709171200).

666778904 is an abundant number, since it is smaller than the sum of its proper divisors (751563496).

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

666778904 is a wasteful number, since it uses less digits than its factorization.

666778904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1424 (or 1420 counting only the distinct ones).

The product of its (nonzero) digits is 3048192, while the sum is 53.

The square root of 666778904 is about 25822.0623498589. The cubic root of 666778904 is about 873.6294861563.

The spelling of 666778904 in words is "six hundred sixty-six million, seven hundred seventy-eight thousand, nine hundred four".