138505 has 4 divisors (see below), whose sum is σ = 166212. Its totient is φ = 110800.

The previous prime is 138497. The next prime is 138511. The reversal of 138505 is 505831.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 505831 = 359 ⋅1409.

It can be written as a sum of positive squares in 2 ways, for example, as 53824 + 84681 = 232^2 + 291^2 .

It is not a de Polignac number, because 138505 - 2³ = 138497 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 an Ulam number.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13846 + ... + 13855.

It is an arithmetic number, because the mean of its divisors is an integer number (41553).

2¹³⁸⁵⁰⁵ is an apocalyptic number.

It is an amenable number.

138505 is a deficient number, since it is larger than the sum of its proper divisors (27707).

138505 is an equidigital number, since it uses as much as digits as its factorization.

138505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27706.

The product of its (nonzero) digits is 600, while the sum is 22.

The square root of 138505 is about 372.1625988731. The cubic root of 138505 is about 51.7394511237.

The spelling of 138505 in words is "one hundred thirty-eight thousand, five hundred five".