665660450881 has 2 divisors, whose sum is σ = 665660450882. Its totient is φ = 665660450880.

The previous prime is 665660450801. The next prime is 665660450893. The reversal of 665660450881 is 188054066566.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 497047560256 + 168612890625 = 705016^2 + 410625^2 .

It is a cyclic number.

It is not a de Polignac number, because 665660450881 - 2⁹ = 665660450369 is a prime.

It is a super-2 number, since 2×665660450881² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (665660450801) 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, 332830225440 + 332830225441.

It is an arithmetic number, because the mean of its divisors is an integer number (332830225441).

Almost surely, 2^665660450881 is an apocalyptic number.

It is an amenable number.

665660450881 is a deficient number, since it is larger than the sum of its proper divisors (1).

665660450881 is an equidigital number, since it uses as much as digits as its factorization.

665660450881 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8294400, while the sum is 55.

The spelling of 665660450881 in words is "six hundred sixty-five billion, six hundred sixty million, four hundred fifty thousand, eight hundred eighty-one".