91189091 has 4 divisors (see below), whose sum is σ = 104216112. Its totient is φ = 78162072.

The previous prime is 91189081. The next prime is 91189099. The reversal of 91189091 is 19098119.

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: 19098119 = 23 ⋅830353.

It is a cyclic number.

It is not a de Polignac number, because 91189091 - 2¹⁰ = 91188067 is a prime.

It is not an unprimeable number, because it can be changed into a prime (91189099) 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, 6513500 + ... + 6513513.

It is an arithmetic number, because the mean of its divisors is an integer number (26054028).

Almost surely, 2^91189091 is an apocalyptic number.

91189091 is a deficient number, since it is larger than the sum of its proper divisors (13027021).

91189091 is a wasteful number, since it uses less digits than its factorization.

91189091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13027020.

The product of its (nonzero) digits is 5832, while the sum is 38.

The square root of 91189091 is about 9549.2979323090. The cubic root of 91189091 is about 450.1054748644.

The spelling of 91189091 in words is "ninety-one million, one hundred eighty-nine thousand, ninety-one".