665039798209 has 2 divisors, whose sum is σ = 665039798210. Its totient is φ = 665039798208.

The previous prime is 665039798201. The next prime is 665039798257. The reversal of 665039798209 is 902897930566.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 636121095184 + 28918703025 = 797572^2 + 170055^2 .

It is a cyclic number.

It is not a de Polignac number, because 665039798209 - 2³ = 665039798201 is a prime.

It is not a weakly prime, because it can be changed into another prime (665039798201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332519899104 + 332519899105.

It is an arithmetic number, because the mean of its divisors is an integer number (332519899105).

Almost surely, 2^665039798209 is an apocalyptic number.

It is an amenable number.

665039798209 is a deficient number, since it is larger than the sum of its proper divisors (1).

665039798209 is an equidigital number, since it uses as much as digits as its factorization.

665039798209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 44089920, while the sum is 64.

The spelling of 665039798209 in words is "six hundred sixty-five billion, thirty-nine million, seven hundred ninety-eight thousand, two hundred nine".