91081090091 has 2 divisors, whose sum is σ = 91081090092. Its totient is φ = 91081090090.

The previous prime is 91081090081. The next prime is 91081090109. The reversal of 91081090091 is 19009018019.

It is a happy number.

Together with next prime (91081090109) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 91081090091 - 2⁶ = 91081090027 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (91081090081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45540545045 + 45540545046.

It is an arithmetic number, because the mean of its divisors is an integer number (45540545046).

Almost surely, 2^91081090091 is an apocalyptic number.

91081090091 is a deficient number, since it is larger than the sum of its proper divisors (1).

91081090091 is an equidigital number, since it uses as much as digits as its factorization.

91081090091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5832, while the sum is 38.

The spelling of 91081090091 in words is "ninety-one billion, eighty-one million, ninety thousand, ninety-one".