668776657 has 2 divisors, whose sum is σ = 668776658. Its totient is φ = 668776656.

The previous prime is 668776639. The next prime is 668776663. The reversal of 668776657 is 756677866.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 607326736 + 61449921 = 24644^2 + 7839^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-668776657 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (668776637) 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, 334388328 + 334388329.

It is an arithmetic number, because the mean of its divisors is an integer number (334388329).

Almost surely, 2^668776657 is an apocalyptic number.

It is an amenable number.

668776657 is a deficient number, since it is larger than the sum of its proper divisors (1).

668776657 is an equidigital number, since it uses as much as digits as its factorization.

668776657 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17781120, while the sum is 58.

The square root of 668776657 is about 25860.7164827272. The cubic root of 668776657 is about 874.5011173023.

The spelling of 668776657 in words is "six hundred sixty-eight million, seven hundred seventy-six thousand, six hundred fifty-seven".