668688 has 20 divisors (see below), whose sum is σ = 1727568. Its totient is φ = 222880.

The previous prime is 668687. The next prime is 668699. The reversal of 668688 is 886866.

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (668687) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6918 + ... + 7013.

2⁶⁶⁸⁶⁸⁸ is an apocalyptic number.

It is an amenable number.

668688 is an abundant number, since it is smaller than the sum of its proper divisors (1058880).

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

668688 is a wasteful number, since it uses less digits than its factorization.

668688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13942 (or 13936 counting only the distinct ones).

The product of its digits is 110592, while the sum is 42.

The square root of 668688 is about 817.7334529050. The cubic root of 668688 is about 87.4462472576.

Subtracting from 668688 its product of digits (110592), we obtain a triangular number (558096 = T₁₀₅₆).

The spelling of 668688 in words is "six hundred sixty-eight thousand, six hundred eighty-eight".