138091 has 4 divisors (see below), whose sum is σ = 146232. Its totient is φ = 129952.

The previous prime is 138079. The next prime is 138101. The reversal of 138091 is 190831.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 190831 = 23 ⋅8297.

It is a cyclic number.

It is not a de Polignac number, because 138091 - 2⁵ = 138059 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (138041) 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, 4045 + ... + 4078.

It is an arithmetic number, because the mean of its divisors is an integer number (36558).

2¹³⁸⁰⁹¹ is an apocalyptic number.

138091 is a deficient number, since it is larger than the sum of its proper divisors (8141).

138091 is an equidigital number, since it uses as much as digits as its factorization.

138091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8140.

The product of its (nonzero) digits is 216, while the sum is 22.

The square root of 138091 is about 371.6059741177. The cubic root of 138091 is about 51.6878488704.

The spelling of 138091 in words is "one hundred thirty-eight thousand, ninety-one".