668904 has 32 divisors (see below), whose sum is σ = 1710720. Its totient is φ = 217856.

The previous prime is 668903. The next prime is 668929. The reversal of 668904 is 409866.

It is a super-2 number, since 2×668904² = 894865122432, which contains 22 as substring.

It is a hoax number, since the sum of its digits (33) coincides with the sum of the digits of its distinct prime factors.

It is a plaindrome in base 14.

It is not an unprimeable number, because it can be changed into a prime (668903) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 832 + ... + 1424.

It is an arithmetic number, because the mean of its divisors is an integer number (53460).

2⁶⁶⁸⁹⁰⁴ 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 668904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (855360).

668904 is an abundant number, since it is smaller than the sum of its proper divisors (1041816).

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

668904 is a wasteful number, since it uses less digits than its factorization.

668904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 649 (or 645 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 33.

The square root of 668904 is about 817.8655146172. The cubic root of 668904 is about 87.4556618905.

The spelling of 668904 in words is "six hundred sixty-eight thousand, nine hundred four".