91020191 has 2 divisors, whose sum is σ = 91020192. Its totient is φ = 91020190.

The previous prime is 91020169. The next prime is 91020199. The reversal of 91020191 is 19102019.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 91020191 - 2¹⁰ = 91019167 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91020199) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45510095 + 45510096.

It is an arithmetic number, because the mean of its divisors is an integer number (45510096).

Almost surely, 2^91020191 is an apocalyptic number.

91020191 is a deficient number, since it is larger than the sum of its proper divisors (1).

91020191 is an equidigital number, since it uses as much as digits as its factorization.

91020191 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 162, while the sum is 23.

The square root of 91020191 is about 9540.4502514294. The cubic root of 91020191 is about 449.8274087106.

The spelling of 91020191 in words is "ninety-one million, twenty thousand, one hundred ninety-one".