66666666666681 has 6 divisors (see below), whose sum is σ = 96296296296330. Its totient is φ = 44444444444448.

The previous prime is 66666666666647. The next prime is 66666666666737. The reversal of 66666666666681 is 18666666666666.

66666666666681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 65652386043456 + 1014280623225 = 8102616^2 + 1007115^2 .

It is not a de Polignac number, because 66666666666681 - 2⁹ = 66666666666169 is a prime.

It is a super-2 number, since 2×66666666666681² (a number of 28 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 66666666666681.

It is not an unprimeable number, because it can be changed into a prime (66666666666641) 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 in 5 ways as a sum of consecutive naturals, for example, 3703703703696 + ... + 3703703703713.

It is an arithmetic number, because the mean of its divisors is an integer number (16049382716055).

Almost surely, 2^{66666666666681} is an apocalyptic number.

It is an amenable number.

66666666666681 is a deficient number, since it is larger than the sum of its proper divisors (29629629629649).

66666666666681 is a wasteful number, since it uses less digits than its factorization.

66666666666681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7407407407415 (or 7407407407412 counting only the distinct ones).

The product of its digits is 17414258688, while the sum is 81.

The spelling of 66666666666681 in words is "sixty-six trillion, six hundred sixty-six billion, six hundred sixty-six million, six hundred sixty-six thousand, six hundred eighty-one".