666700406681 has 2 divisors, whose sum is σ = 666700406682. Its totient is φ = 666700406680.

The previous prime is 666700406657. The next prime is 666700406717. The reversal of 666700406681 is 186604007666.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 638305123600 + 28395283081 = 798940^2 + 168509^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-666700406681 is a prime.

It is a super-2 number, since 2×666700406681² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (666700406651) 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, 333350203340 + 333350203341.

It is an arithmetic number, because the mean of its divisors is an integer number (333350203341).

Almost surely, 2^666700406681 is an apocalyptic number.

It is an amenable number.

666700406681 is a deficient number, since it is larger than the sum of its proper divisors (1).

666700406681 is an equidigital number, since it uses as much as digits as its factorization.

666700406681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1741824, while the sum is 50.

The spelling of 666700406681 in words is "six hundred sixty-six billion, seven hundred million, four hundred six thousand, six hundred eighty-one".