668894729 has 2 divisors, whose sum is σ = 668894730. Its totient is φ = 668894728.

The previous prime is 668894689. The next prime is 668894747. The reversal of 668894729 is 927498866.

668894729 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., 545129104 + 123765625 = 23348^2 + 11125^2 .

It is a cyclic number.

It is not a de Polignac number, because 668894729 - 2¹² = 668890633 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (668894749) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334447364 + 334447365.

It is an arithmetic number, because the mean of its divisors is an integer number (334447365).

Almost surely, 2^668894729 is an apocalyptic number.

It is an amenable number.

668894729 is a deficient number, since it is larger than the sum of its proper divisors (1).

668894729 is an equidigital number, since it uses as much as digits as its factorization.

668894729 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10450944, while the sum is 59.

The square root of 668894729 is about 25862.9992266945. Note that the first 3 decimals coincide. The cubic root of 668894729 is about 874.5525784386.

The spelling of 668894729 in words is "six hundred sixty-eight million, eight hundred ninety-four thousand, seven hundred twenty-nine".