66040404373681 has 2 divisors, whose sum is σ = 66040404373682. Its totient is φ = 66040404373680.

The previous prime is 66040404373679. The next prime is 66040404373759. The reversal of 66040404373681 is 18637340404066.

66040404373681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 35596318050225 + 30444086323456 = 5966265^2 + 5517616^2 .

It is a cyclic number.

It is not a de Polignac number, because 66040404373681 - 2¹ = 66040404373679 is a prime.

It is a super-2 number, since 2×66040404373681² (a number of 28 digits) contains 22 as substring.

Together with 66040404373679, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (66040404373981) 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, 33020202186840 + 33020202186841.

It is an arithmetic number, because the mean of its divisors is an integer number (33020202186841).

Almost surely, 2^{66040404373681} is an apocalyptic number.

It is an amenable number.

66040404373681 is a deficient number, since it is larger than the sum of its proper divisors (1).

66040404373681 is an equidigital number, since it uses as much as digits as its factorization.

66040404373681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6967296, while the sum is 52.

The spelling of 66040404373681 in words is "sixty-six trillion, forty billion, four hundred four million, three hundred seventy-three thousand, six hundred eighty-one".