138591 has 20 divisors (see below), whose sum is σ = 217800. Its totient is φ = 87696.

The previous prime is 138587. The next prime is 138599. The reversal of 138591 is 195831.

It is not a de Polignac number, because 138591 - 2² = 138587 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 138591.

It is not an unprimeable number, because it can be changed into a prime (138599) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 2320 + ... + 2378.

It is an arithmetic number, because the mean of its divisors is an integer number (10890).

2¹³⁸⁵⁹¹ is an apocalyptic number.

138591 is a deficient number, since it is larger than the sum of its proper divisors (79209).

138591 is an equidigital number, since it uses as much as digits as its factorization.

138591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 100 (or 91 counting only the distinct ones).

The product of its digits is 1080, while the sum is 27.

The square root of 138591 is about 372.2781218390. The cubic root of 138591 is about 51.7501575295.

It can be divided in two parts, 138 and 591, that added together give a 6-th power (729 = 3⁶).

The spelling of 138591 in words is "one hundred thirty-eight thousand, five hundred ninety-one".