91891971 has 6 divisors (see below), whose sum is σ = 132732860. Its totient is φ = 61261308.

The previous prime is 91891949. The next prime is 91891973. The reversal of 91891971 is 17919819.

It is not a de Polignac number, because 91891971 - 2¹⁰ = 91890947 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91891973) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 5105101 + ... + 5105118.

Almost surely, 2^91891971 is an apocalyptic number.

91891971 is a deficient number, since it is larger than the sum of its proper divisors (40840889).

91891971 is a wasteful number, since it uses less digits than its factorization.

91891971 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10210225 (or 10210222 counting only the distinct ones).

The product of its digits is 40824, while the sum is 45.

The square root of 91891971 is about 9586.0299916076. The cubic root of 91891971 is about 451.2589781390.

The spelling of 91891971 in words is "ninety-one million, eight hundred ninety-one thousand, nine hundred seventy-one".