668939 has 2 divisors, whose sum is σ = 668940. Its totient is φ = 668938.

The previous prime is 668929. The next prime is 668947. The reversal of 668939 is 939866.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 668939 - 2¹² = 664843 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 668896 and 668905.

It is not a weakly prime, because it can be changed into another prime (668929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334469 + 334470.

It is an arithmetic number, because the mean of its divisors is an integer number (334470).

2⁶⁶⁸⁹³⁹ is an apocalyptic number.

668939 is a deficient number, since it is larger than the sum of its proper divisors (1).

668939 is an equidigital number, since it uses as much as digits as its factorization.

668939 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 69984, while the sum is 41.

The square root of 668939 is about 817.8869114982. The cubic root of 668939 is about 87.4571872189.

The spelling of 668939 in words is "six hundred sixty-eight thousand, nine hundred thirty-nine".