668319857 has 2 divisors, whose sum is σ = 668319858. Its totient is φ = 668319856.

The previous prime is 668319829. The next prime is 668319859. The reversal of 668319857 is 758913866.

It is a happy number.

668319857 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 404452321 + 263867536 = 20111^2 + 16244^2 .

It is a cyclic number.

It is not a de Polignac number, because 668319857 - 2¹⁸ = 668057713 is a prime.

Together with 668319859, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 668319799 and 668319808.

It is not a weakly prime, because it can be changed into another prime (668319859) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334159928 + 334159929.

It is an arithmetic number, because the mean of its divisors is an integer number (334159929).

Almost surely, 2^668319857 is an apocalyptic number.

It is an amenable number.

668319857 is a deficient number, since it is larger than the sum of its proper divisors (1).

668319857 is an equidigital number, since it uses as much as digits as its factorization.

668319857 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2177280, while the sum is 53.

The square root of 668319857 is about 25851.8830455346. The cubic root of 668319857 is about 874.3019660649.

The spelling of 668319857 in words is "six hundred sixty-eight million, three hundred nineteen thousand, eight hundred fifty-seven".