668816 has 10 divisors (see below), whose sum is σ = 1295862. Its totient is φ = 334400.

The previous prime is 668813. The next prime is 668821. The reversal of 668816 is 618866.

It can be written as a sum of positive squares in only one way, i.e., 355216 + 313600 = 596^2 + 560^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668813) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20885 + ... + 20916.

2⁶⁶⁸⁸¹⁶ is an apocalyptic number.

It is an amenable number.

668816 is a deficient number, since it is larger than the sum of its proper divisors (627046).

668816 is a wasteful number, since it uses less digits than its factorization.

668816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41809 (or 41803 counting only the distinct ones).

The product of its digits is 13824, while the sum is 35.

The square root of 668816 is about 817.8117142717. The cubic root of 668816 is about 87.4518265440.

The spelling of 668816 in words is "six hundred sixty-eight thousand, eight hundred sixteen".