91971983 has 4 divisors (see below), whose sum is σ = 92042928. Its totient is φ = 91901040.

The previous prime is 91971953. The next prime is 91972007. The reversal of 91971983 is 38917919.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 38917919 = 1747 ⋅22277.

It is a cyclic number.

It is not a de Polignac number, because 91971983 - 2¹⁰ = 91970959 is a prime.

It is a super-3 number, since 3×91971983³ (a number of 25 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91971923) 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, 33491 + ... + 36132.

It is an arithmetic number, because the mean of its divisors is an integer number (23010732).

Almost surely, 2^91971983 is an apocalyptic number.

91971983 is a deficient number, since it is larger than the sum of its proper divisors (70945).

91971983 is a wasteful number, since it uses less digits than its factorization.

91971983 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70944.

The product of its digits is 122472, while the sum is 47.

The square root of 91971983 is about 9590.2024483324. The cubic root of 91971983 is about 451.3899132599.

The spelling of 91971983 in words is "ninety-one million, nine hundred seventy-one thousand, nine hundred eighty-three".