666661117 has 2 divisors, whose sum is σ = 666661118. Its totient is φ = 666661116.

The previous prime is 666661111. The next prime is 666661129. The reversal of 666661117 is 711166666.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 650709081 + 15952036 = 25509^2 + 3994^2 .

It is a cyclic number.

It is not a de Polignac number, because 666661117 - 2³ = 666661109 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 666661117.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (666661111) 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, 333330558 + 333330559.

It is an arithmetic number, because the mean of its divisors is an integer number (333330559).

Almost surely, 2^666661117 is an apocalyptic number.

It is an amenable number.

666661117 is a deficient number, since it is larger than the sum of its proper divisors (1).

666661117 is an equidigital number, since it uses as much as digits as its factorization.

666661117 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 54432, while the sum is 40.

The square root of 666661117 is about 25819.7815056596. The cubic root of 666661117 is about 873.5780406894.

The spelling of 666661117 in words is "six hundred sixty-six million, six hundred sixty-one thousand, one hundred seventeen".