665407217129 has 2 divisors, whose sum is σ = 665407217130. Its totient is φ = 665407217128.

The previous prime is 665407217107. The next prime is 665407217183. The reversal of 665407217129 is 921712704566.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 658597171600 + 6810045529 = 811540^2 + 82523^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-665407217129 is a prime.

It is not a weakly prime, because it can be changed into another prime (665407210129) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332703608564 + 332703608565.

It is an arithmetic number, because the mean of its divisors is an integer number (332703608565).

Almost surely, 2^665407217129 is an apocalyptic number.

It is an amenable number.

665407217129 is a deficient number, since it is larger than the sum of its proper divisors (1).

665407217129 is an equidigital number, since it uses as much as digits as its factorization.

665407217129 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1270080, while the sum is 50.

The spelling of 665407217129 in words is "six hundred sixty-five billion, four hundred seven million, two hundred seventeen thousand, one hundred twenty-nine".