91998791 has 4 divisors (see below), whose sum is σ = 92018472. Its totient is φ = 91979112.

The previous prime is 91998773. The next prime is 91998833. The reversal of 91998791 is 19789919.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19789919 = 29 ⋅682411.

It is a cyclic number.

It is not a de Polignac number, because 91998791 - 2⁶ = 91998727 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 (91998691) 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, 1625 + ... + 13661.

It is an arithmetic number, because the mean of its divisors is an integer number (23004618).

Almost surely, 2^91998791 is an apocalyptic number.

91998791 is a deficient number, since it is larger than the sum of its proper divisors (19681).

91998791 is a wasteful number, since it uses less digits than its factorization.

91998791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19680.

The product of its digits is 367416, while the sum is 53.

The square root of 91998791 is about 9591.6000229367. The cubic root of 91998791 is about 451.4337660539.

The spelling of 91998791 in words is "ninety-one million, nine hundred ninety-eight thousand, seven hundred ninety-one".