191940091 has 4 divisors (see below), whose sum is σ = 219360112. Its totient is φ = 164520072.

The previous prime is 191940079. The next prime is 191940101. The reversal of 191940091 is 190049191.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 190049191 = 19 ⋅10002589.

It is a cyclic number.

It is not a de Polignac number, because 191940091 - 2¹⁹ = 191415803 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (191940031) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13710000 + ... + 13710013.

It is an arithmetic number, because the mean of its divisors is an integer number (54840028).

Almost surely, 2^191940091 is an apocalyptic number.

191940091 is a deficient number, since it is larger than the sum of its proper divisors (27420021).

191940091 is an equidigital number, since it uses as much as digits as its factorization.

191940091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27420020.

The product of its (nonzero) digits is 2916, while the sum is 34.

The square root of 191940091 is about 13854.2445120620. The cubic root of 191940091 is about 576.8398192912.

The spelling of 191940091 in words is "one hundred ninety-one million, nine hundred forty thousand, ninety-one".