668786 has 4 divisors (see below), whose sum is σ = 1003182. Its totient is φ = 334392.

The previous prime is 668761. The next prime is 668791. The reversal of 668786 is 687866.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 687866 = 2 ⋅343933.

It can be written as a sum of positive squares in only one way, i.e., 483025 + 185761 = 695^2 + 431^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 167195 + ... + 167198.

2⁶⁶⁸⁷⁸⁶ is an apocalyptic number.

668786 is a deficient number, since it is larger than the sum of its proper divisors (334396).

668786 is a wasteful number, since it uses less digits than its factorization.

668786 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 334395.

The product of its digits is 96768, while the sum is 41.

The square root of 668786 is about 817.7933724358. The cubic root of 668786 is about 87.4505189626.

The spelling of 668786 in words is "six hundred sixty-eight thousand, seven hundred eighty-six".