191091191 has 2 divisors, whose sum is σ = 191091192. Its totient is φ = 191091190.

The previous prime is 191091181. The next prime is 191091217. The reversal of 191091191 is 191190191.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 191091191 - 2²² = 186896887 is a prime.

It is equal to p_10612598 and since 191091191 and 10612598 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (191091181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 95545595 + 95545596.

It is an arithmetic number, because the mean of its divisors is an integer number (95545596).

Almost surely, 2^191091191 is an apocalyptic number.

191091191 is a deficient number, since it is larger than the sum of its proper divisors (1).

191091191 is an equidigital number, since it uses as much as digits as its factorization.

191091191 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 729, while the sum is 32.

The square root of 191091191 is about 13823.5737419815. The cubic root of 191091191 is about 575.9881594386.

The spelling of 191091191 in words is "one hundred ninety-one million, ninety-one thousand, one hundred ninety-one".