91509 has 16 divisors (see below), whose sum is σ = 138240. Its totient is φ = 53360.

The previous prime is 91499. The next prime is 91513. The reversal of 91509 is 90519.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 91509 - 2⁴ = 91493 is a prime.

91509 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91529) 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, 1522 + ... + 1580.

It is an arithmetic number, because the mean of its divisors is an integer number (8640).

2⁹¹⁵⁰⁹ is an apocalyptic number.

It is an amenable number.

91509 is a deficient number, since it is larger than the sum of its proper divisors (46731).

91509 is a wasteful number, since it uses less digits than its factorization.

91509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 120.

The product of its (nonzero) digits is 405, while the sum is 24.

The square root of 91509 is about 302.5045454204. The cubic root of 91509 is about 45.0631212952.

Subtracting from 91509 its reverse (90519), we obtain a triangular number (990 = T₄₄).

The spelling of 91509 in words is "ninety-one thousand, five hundred nine".