191381999 has 2 divisors, whose sum is σ = 191382000. Its totient is φ = 191381998.

The previous prime is 191381987. The next prime is 191382031. The reversal of 191381999 is 999183191.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 191381999 - 2²⁴ = 174604783 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (191381909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 95690999 + 95691000.

It is an arithmetic number, because the mean of its divisors is an integer number (95691000).

Almost surely, 2^191381999 is an apocalyptic number.

191381999 is a deficient number, since it is larger than the sum of its proper divisors (1).

191381999 is an equidigital number, since it uses as much as digits as its factorization.

191381999 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 157464, while the sum is 50.

The square root of 191381999 is about 13834.0882966678. The cubic root of 191381999 is about 576.2801963902.

The spelling of 191381999 in words is "one hundred ninety-one million, three hundred eighty-one thousand, nine hundred ninety-nine".