91870091 has 4 divisors (see below), whose sum is σ = 97274232. Its totient is φ = 86465952.

The previous prime is 91870067. The next prime is 91870099. The reversal of 91870091 is 19007819.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91870091 is a prime.

It is a super-2 number, since 2×91870091² = 16880227240696562, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91870099) 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, 2702045 + ... + 2702078.

It is an arithmetic number, because the mean of its divisors is an integer number (24318558).

Almost surely, 2^91870091 is an apocalyptic number.

91870091 is a deficient number, since it is larger than the sum of its proper divisors (5404141).

91870091 is a wasteful number, since it uses less digits than its factorization.

91870091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5404140.

The product of its (nonzero) digits is 4536, while the sum is 35.

The square root of 91870091 is about 9584.8886795831. Note that the first 3 decimals coincide. The cubic root of 91870091 is about 451.2231595211.

The spelling of 91870091 in words is "ninety-one million, eight hundred seventy thousand, ninety-one".