191380991 has 2 divisors, whose sum is σ = 191380992. Its totient is φ = 191380990.

The previous prime is 191380967. The next prime is 191380993. The reversal of 191380991 is 199083191.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 191380991 - 2⁶ = 191380927 is a prime.

It is a super-2 number, since 2×191380991² = 73253367432284162, which contains 22 as substring.

Together with 191380993, 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 (191380993) 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, 95690495 + 95690496.

It is an arithmetic number, because the mean of its divisors is an integer number (95690496).

Almost surely, 2^191380991 is an apocalyptic number.

191380991 is a deficient number, since it is larger than the sum of its proper divisors (1).

191380991 is an equidigital number, since it uses as much as digits as its factorization.

191380991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 17496, while the sum is 41.

The square root of 191380991 is about 13834.0518648731. The cubic root of 191380991 is about 576.2791846415.

The spelling of 191380991 in words is "one hundred ninety-one million, three hundred eighty thousand, nine hundred ninety-one".