138609 has 6 divisors (see below), whose sum is σ = 200226. Its totient is φ = 92400.

The previous prime is 138599. The next prime is 138617. The reversal of 138609 is 906831.

138609 is nontrivially palindromic in base 11.

138609 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 138384 + 225 = 372^2 + 15^2 .

It is not a de Polignac number, because 138609 - 2⁵ = 138577 is a prime.

It is not an unprimeable number, because it can be changed into a prime (138629) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 7692 + ... + 7709.

It is an arithmetic number, because the mean of its divisors is an integer number (33371).

2¹³⁸⁶⁰⁹ is an apocalyptic number.

It is an amenable number.

138609 is a deficient number, since it is larger than the sum of its proper divisors (61617).

138609 is a wasteful number, since it uses less digits than its factorization.

138609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15407 (or 15404 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

The square root of 138609 is about 372.3022965280. The cubic root of 138609 is about 51.7523978445.

It can be divided in two parts, 138 and 609, that added together give a palindrome (747).

The spelling of 138609 in words is "one hundred thirty-eight thousand, six hundred nine".