668556 has 54 divisors (see below), whose sum is σ = 1971060. Its totient is φ = 190512.

The previous prime is 668543. The next prime is 668567. The reversal of 668556 is 655866.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 668556.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 1575 + ... + 1953.

2⁶⁶⁸⁵⁵⁶ 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 668556, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (985530).

668556 is an abundant number, since it is smaller than the sum of its proper divisors (1302504).

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

668556 is a wasteful number, since it uses less digits than its factorization.

668556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 403 (or 391 counting only the distinct ones).

The product of its digits is 43200, while the sum is 36.

The square root of 668556 is about 817.6527380251. The cubic root of 668556 is about 87.4404928728.

The spelling of 668556 in words is "six hundred sixty-eight thousand, five hundred fifty-six".