91771959 has 4 divisors (see below), whose sum is σ = 122362616. Its totient is φ = 61181304.

The previous prime is 91771903. The next prime is 91771961. The reversal of 91771959 is 95917719.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 91771959 - 2⁸ = 91771703 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91771969) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15295324 + ... + 15295329.

It is an arithmetic number, because the mean of its divisors is an integer number (30590654).

Almost surely, 2^91771959 is an apocalyptic number.

91771959 is a deficient number, since it is larger than the sum of its proper divisors (30590657).

91771959 is a wasteful number, since it uses less digits than its factorization.

91771959 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30590656.

The product of its digits is 178605, while the sum is 48.

The square root of 91771959 is about 9579.7682122273. The cubic root of 91771959 is about 451.0624427023.

Subtracting 91771959 from its reverse (95917719), we obtain a triangular number (4145760 = T₂₈₇₉).

The spelling of 91771959 in words is "ninety-one million, seven hundred seventy-one thousand, nine hundred fifty-nine".