668739613 has 2 divisors, whose sum is σ = 668739614. Its totient is φ = 668739612.

The previous prime is 668739527. The next prime is 668739629. The reversal of 668739613 is 316937866.

668739613 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., 652393764 + 16345849 = 25542^2 + 4043^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-668739613 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (668734613) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334369806 + 334369807.

It is an arithmetic number, because the mean of its divisors is an integer number (334369807).

Almost surely, 2^668739613 is an apocalyptic number.

It is an amenable number.

668739613 is a deficient number, since it is larger than the sum of its proper divisors (1).

668739613 is an equidigital number, since it uses as much as digits as its factorization.

668739613 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 979776, while the sum is 49.

The square root of 668739613 is about 25860.0002513534. Note that the first 3 decimals coincide. The cubic root of 668739613 is about 874.4849705977.

The spelling of 668739613 in words is "six hundred sixty-eight million, seven hundred thirty-nine thousand, six hundred thirteen".