668528639 has 2 divisors, whose sum is σ = 668528640. Its totient is φ = 668528638.

The previous prime is 668528629. The next prime is 668528659. The reversal of 668528639 is 936825866.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-668528639 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (668528629) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334264319 + 334264320.

It is an arithmetic number, because the mean of its divisors is an integer number (334264320).

Almost surely, 2^668528639 is an apocalyptic number.

668528639 is a deficient number, since it is larger than the sum of its proper divisors (1).

668528639 is an equidigital number, since it uses as much as digits as its factorization.

668528639 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3732480, while the sum is 53.

The square root of 668528639 is about 25855.9207726200. The cubic root of 668528639 is about 874.3930000741.

The spelling of 668528639 in words is "six hundred sixty-eight million, five hundred twenty-eight thousand, six hundred thirty-nine".