666558565855657 has 2 divisors, whose sum is σ = 666558565855658. Its totient is φ = 666558565855656.

The previous prime is 666558565855643. The next prime is 666558565855711. The reversal of 666558565855657 is 756558565855666.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 666514184428096 + 44381427561 = 25816936^2 + 210669^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-666558565855657 is a prime.

It is not a weakly prime, because it can be changed into another prime (666558565855757) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333279282927828 + 333279282927829.

It is an arithmetic number, because the mean of its divisors is an integer number (333279282927829).

Almost surely, 2^{666558565855657} is an apocalyptic number.

It is an amenable number.

666558565855657 is a deficient number, since it is larger than the sum of its proper divisors (1).

666558565855657 is an equidigital number, since it uses as much as digits as its factorization.

666558565855657 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 272160000000, while the sum is 88.

Subtracting 666558565855657 from its reverse (756558565855666), we obtain a palindrome (90000000000009).

The spelling of 666558565855657 in words is "six hundred sixty-six trillion, five hundred fifty-eight billion, five hundred sixty-five million, eight hundred fifty-five thousand, six hundred fifty-seven".