668827409 has 2 divisors, whose sum is σ = 668827410. Its totient is φ = 668827408.

The previous prime is 668827403. The next prime is 668827421. The reversal of 668827409 is 904728866.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 603783184 + 65044225 = 24572^2 + 8065^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-668827409 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (668827403) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334413704 + 334413705.

It is an arithmetic number, because the mean of its divisors is an integer number (334413705).

Almost surely, 2^668827409 is an apocalyptic number.

It is an amenable number.

668827409 is a deficient number, since it is larger than the sum of its proper divisors (1).

668827409 is an equidigital number, since it uses as much as digits as its factorization.

668827409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1161216, while the sum is 50.

The square root of 668827409 is about 25861.6977207607. The cubic root of 668827409 is about 874.5232380695.

The spelling of 668827409 in words is "six hundred sixty-eight million, eight hundred twenty-seven thousand, four hundred nine".