199991117 has 2 divisors, whose sum is σ = 199991118. Its totient is φ = 199991116.

The previous prime is 199991087. The next prime is 199991119. The reversal of 199991117 is 711199991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 138744841 + 61246276 = 11779^2 + 7826^2 .

It is an emirp because it is prime and its reverse (711199991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 199991117 - 2⁶ = 199991053 is a prime.

Together with 199991119, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (199991119) 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, 99995558 + 99995559.

It is an arithmetic number, because the mean of its divisors is an integer number (99995559).

Almost surely, 2^199991117 is an apocalyptic number.

It is an amenable number.

199991117 is a deficient number, since it is larger than the sum of its proper divisors (1).

199991117 is an equidigital number, since it uses as much as digits as its factorization.

199991117 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 45927, while the sum is 47.

The square root of 199991117 is about 14141.8215587667. The cubic root of 199991117 is about 584.7948894979.

The spelling of 199991117 in words is "one hundred ninety-nine million, nine hundred ninety-one thousand, one hundred seventeen".