91991171 has 2 divisors, whose sum is σ = 91991172. Its totient is φ = 91991170.

The previous prime is 91991117. The next prime is 91991177. The reversal of 91991171 is 17119919.

Together with previous prime (91991117) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 91991171 - 2¹⁴ = 91974787 is a prime.

It is not a weakly prime, because it can be changed into another prime (91991177) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45995585 + 45995586.

It is an arithmetic number, because the mean of its divisors is an integer number (45995586).

Almost surely, 2^91991171 is an apocalyptic number.

91991171 is a deficient number, since it is larger than the sum of its proper divisors (1).

91991171 is an equidigital number, since it uses as much as digits as its factorization.

91991171 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5103, while the sum is 38.

The square root of 91991171 is about 9591.2027921424. The cubic root of 91991171 is about 451.4213020485.

The spelling of 91991171 in words is "ninety-one million, nine hundred ninety-one thousand, one hundred seventy-one".