91131591 has 16 divisors (see below), whose sum is σ = 124299648. Its totient is φ = 59373600.

The previous prime is 91131587. The next prime is 91131641. The reversal of 91131591 is 19513119.

It is not a de Polignac number, because 91131591 - 2² = 91131587 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91131511) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24601 + ... + 28061.

It is an arithmetic number, because the mean of its divisors is an integer number (7768728).

Almost surely, 2^91131591 is an apocalyptic number.

91131591 is a deficient number, since it is larger than the sum of its proper divisors (33168057).

91131591 is a wasteful number, since it uses less digits than its factorization.

91131591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3662.

The product of its digits is 1215, while the sum is 30.

The square root of 91131591 is about 9546.2867650202. The cubic root of 91131591 is about 450.0108491212.

The spelling of 91131591 in words is "ninety-one million, one hundred thirty-one thousand, five hundred ninety-one".