91091 has 18 divisors (see below), whose sum is σ = 125172. Its totient is φ = 65520.

The previous prime is 91081. The next prime is 91097. The reversal of 91091 is 19019.

91091 = 28² + 29² + ... + 66².

It is not a de Polignac number, because 91091 - 2¹⁰ = 90067 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91097) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 7001 + ... + 7013.

It is an arithmetic number, because the mean of its divisors is an integer number (6954).

2⁹¹⁰⁹¹ is an apocalyptic number.

91091 is a gapful number since it is divisible by the number (91) formed by its first and last digit.

91091 is a deficient number, since it is larger than the sum of its proper divisors (34081).

91091 is a wasteful number, since it uses less digits than its factorization.

91091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51 (or 31 counting only the distinct ones).

The product of its (nonzero) digits is 81, while the sum is 20.

The square root of 91091 is about 301.8128559223. The cubic root of 91091 is about 44.9944025960.

It can be divided in two parts, 910 and 91, that added together give a palindrome (1001).

The spelling of 91091 in words is "ninety-one thousand, ninety-one".