91811279 has 4 divisors (see below), whose sum is σ = 104927184. Its totient is φ = 78695376.

The previous prime is 91811261. The next prime is 91811309. The reversal of 91811279 is 97211819.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 97211819 = 983 ⋅98893.

It is a cyclic number.

It is not a de Polignac number, because 91811279 - 2²⁰ = 90762703 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 (91811479) 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, 6557942 + ... + 6557955.

It is an arithmetic number, because the mean of its divisors is an integer number (26231796).

Almost surely, 2^91811279 is an apocalyptic number.

91811279 is a deficient number, since it is larger than the sum of its proper divisors (13115905).

91811279 is a wasteful number, since it uses less digits than its factorization.

91811279 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13115904.

The product of its digits is 9072, while the sum is 38.

The square root of 91811279 is about 9581.8202341726. The cubic root of 91811279 is about 451.1268532371.

The spelling of 91811279 in words is "ninety-one million, eight hundred eleven thousand, two hundred seventy-nine".