668811931 has 2 divisors, whose sum is σ = 668811932. Its totient is φ = 668811930.

The previous prime is 668811907. The next prime is 668811937. The reversal of 668811931 is 139118866.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 668811931 - 2¹⁹ = 668287643 is a prime.

It is a super-2 number, since 2×668811931² = 894618798095897522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (668811937) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334405965 + 334405966.

It is an arithmetic number, because the mean of its divisors is an integer number (334405966).

Almost surely, 2^668811931 is an apocalyptic number.

668811931 is a deficient number, since it is larger than the sum of its proper divisors (1).

668811931 is an equidigital number, since it uses as much as digits as its factorization.

668811931 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 62208, while the sum is 43.

The square root of 668811931 is about 25861.3984734005. The cubic root of 668811931 is about 874.5164919469.

The spelling of 668811931 in words is "six hundred sixty-eight million, eight hundred eleven thousand, nine hundred thirty-one".