668686729 has 2 divisors, whose sum is σ = 668686730. Its totient is φ = 668686728.

The previous prime is 668686723. The next prime is 668686747. The reversal of 668686729 is 927686866.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 612661504 + 56025225 = 24752^2 + 7485^2 .

It is a cyclic number.

It is not a de Polignac number, because 668686729 - 2¹³ = 668678537 is a prime.

It is not a weakly prime, because it can be changed into another prime (668686723) 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, 334343364 + 334343365.

It is an arithmetic number, because the mean of its divisors is an integer number (334343365).

Almost surely, 2^668686729 is an apocalyptic number.

It is an amenable number.

668686729 is a deficient number, since it is larger than the sum of its proper divisors (1).

668686729 is an equidigital number, since it uses as much as digits as its factorization.

668686729 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10450944, while the sum is 58.

The square root of 668686729 is about 25858.9777253471. The cubic root of 668686729 is about 874.4619185350.

The spelling of 668686729 in words is "six hundred sixty-eight million, six hundred eighty-six thousand, seven hundred twenty-nine".