668979 has 12 divisors (see below), whose sum is σ = 1002456. Its totient is φ = 445824.

The previous prime is 668963. The next prime is 668989. The reversal of 668979 is 979866.

668979 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 668979 - 2⁴ = 668963 is a prime.

668979 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (668929) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1134 + ... + 1619.

It is an arithmetic number, because the mean of its divisors is an integer number (83538).

2⁶⁶⁸⁹⁷⁹ is an apocalyptic number.

668979 is a deficient number, since it is larger than the sum of its proper divisors (333477).

668979 is an equidigital number, since it uses as much as digits as its factorization.

668979 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2768 (or 2756 counting only the distinct ones).

The product of its digits is 163296, while the sum is 45.

The square root of 668979 is about 817.9113643910. The cubic root of 668979 is about 87.4589303862.

It can be divided in two parts, 66 and 8979, that added together give a triangular number (9045 = T₁₃₄).

The spelling of 668979 in words is "six hundred sixty-eight thousand, nine hundred seventy-nine".