668555904 has 128 divisors (see below), whose sum is σ = 1885939200. Its totient is φ = 209386496.

The previous prime is 668555887. The next prime is 668555933. The reversal of 668555904 is 409555866.

It is a tau number, because it is divible by the number of its divisors (128).

It is a Harshad number since it is a multiple of its sum of digits (48).

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, 520447 + ... + 521729.

It is an arithmetic number, because the mean of its divisors is an integer number (14733900).

Almost surely, 2^668555904 is an apocalyptic number.

668555904 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 668555904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (942969600).

668555904 is an abundant number, since it is smaller than the sum of its proper divisors (1217383296).

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

668555904 is a wasteful number, since it uses less digits than its factorization.

668555904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1382 (or 1370 counting only the distinct ones).

The product of its (nonzero) digits is 1296000, while the sum is 48.

The square root of 668555904 is about 25856.4480159205. The cubic root of 668555904 is about 874.4048868753.

The spelling of 668555904 in words is "six hundred sixty-eight million, five hundred fifty-five thousand, nine hundred four".