91991187 has 8 divisors (see below), whose sum is σ = 136283280. Its totient is φ = 61327440.

The previous prime is 91991183. The next prime is 91991197. The reversal of 91991187 is 78119919.

It is not a de Polignac number, because 91991187 - 2² = 91991183 is a prime.

It is not an unprimeable number, because it can be changed into a prime (91991183) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1703514 + ... + 1703567.

It is an arithmetic number, because the mean of its divisors is an integer number (17035410).

Almost surely, 2^91991187 is an apocalyptic number.

91991187 is a deficient number, since it is larger than the sum of its proper divisors (44292093).

91991187 is a wasteful number, since it uses less digits than its factorization.

91991187 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3407090 (or 3407084 counting only the distinct ones).

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

The square root of 91991187 is about 9591.2036262400. The cubic root of 91991187 is about 451.4213282204.

The spelling of 91991187 in words is "ninety-one million, nine hundred ninety-one thousand, one hundred eighty-seven".