668656 has 30 divisors (see below), whose sum is σ = 1371440. Its totient is φ = 315744.

The previous prime is 668623. The next prime is 668671. The reversal of 668656 is 656866.

668656 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 8425 + ... + 8503.

2⁶⁶⁸⁶⁵⁶ 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 668656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (685720).

668656 is an abundant number, since it is smaller than the sum of its proper divisors (702784).

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

668656 is a wasteful number, since it uses less digits than its factorization.

668656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 133 (or 104 counting only the distinct ones).

The product of its digits is 51840, while the sum is 37.

The square root of 668656 is about 817.7138863930. The cubic root of 668656 is about 87.4448523248. Note that the first 3 decimals are identical.

The spelling of 668656 in words is "six hundred sixty-eight thousand, six hundred fifty-six".