66991117 has 2 divisors, whose sum is σ = 66991118. Its totient is φ = 66991116.

The previous prime is 66991087. The next prime is 66991163. The reversal of 66991117 is 71119966.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 64738116 + 2253001 = 8046^2 + 1501^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66991117 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66991117.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66991187) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33495558 + 33495559.

It is an arithmetic number, because the mean of its divisors is an integer number (33495559).

Almost surely, 2^66991117 is an apocalyptic number.

It is an amenable number.

66991117 is a deficient number, since it is larger than the sum of its proper divisors (1).

66991117 is an equidigital number, since it uses as much as digits as its factorization.

66991117 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20412, while the sum is 40.

The square root of 66991117 is about 8184.8101382989. The cubic root of 66991117 is about 406.1368596334.

The spelling of 66991117 in words is "sixty-six million, nine hundred ninety-one thousand, one hundred seventeen".