666566631361 has 2 divisors, whose sum is σ = 666566631362. Its totient is φ = 666566631360.

The previous prime is 666566631347. The next prime is 666566631407. The reversal of 666566631361 is 163136665666.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 648941413761 + 17625217600 = 805569^2 + 132760^2 .

It is a cyclic number.

It is not a de Polignac number, because 666566631361 - 2¹⁷ = 666566500289 is a prime.

It is a super-2 number, since 2×666566631361² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (666566631461) 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, 333283315680 + 333283315681.

It is an arithmetic number, because the mean of its divisors is an integer number (333283315681).

Almost surely, 2^666566631361 is an apocalyptic number.

It is an amenable number.

666566631361 is a deficient number, since it is larger than the sum of its proper divisors (1).

666566631361 is an equidigital number, since it uses as much as digits as its factorization.

666566631361 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12597120, while the sum is 55.

The spelling of 666566631361 in words is "six hundred sixty-six billion, five hundred sixty-six million, six hundred thirty-one thousand, three hundred sixty-one".