668680 has 32 divisors (see below), whose sum is σ = 1531800. Its totient is φ = 262656.

The previous prime is 668677. The next prime is 668687. The reversal of 668680 is 86866.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 649636 + 19044 = 806^2 + 138^2 .

It is a Smith number, since the sum of its digits (34) coincides with the sum of the digits of its prime factors.

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 7 ways as a sum of consecutive naturals, for example, 2806 + ... + 3034.

2⁶⁶⁸⁶⁸⁰ 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 668680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (765900).

668680 is an abundant number, since it is smaller than the sum of its proper divisors (863120).

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

668680 is a wasteful number, since it uses less digits than its factorization.

668680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 313 (or 309 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 34.

The square root of 668680 is about 817.7285613209. The cubic root of 668680 is about 87.4458985286.

It can be divided in two parts, 6 and 68680, that added together give a palindrome (68686).

The spelling of 668680 in words is "six hundred sixty-eight thousand, six hundred eighty".