138909 has 8 divisors (see below), whose sum is σ = 195040. Its totient is φ = 87696.

The previous prime is 138899. The next prime is 138917. The reversal of 138909 is 909831.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 138909 - 2⁴ = 138893 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138959) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1162 + ... + 1275.

It is an arithmetic number, because the mean of its divisors is an integer number (24380).

2¹³⁸⁹⁰⁹ is an apocalyptic number.

138909 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

It is an amenable number.

138909 is a deficient number, since it is larger than the sum of its proper divisors (56131).

138909 is a wasteful number, since it uses less digits than its factorization.

138909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2459.

The product of its (nonzero) digits is 1944, while the sum is 30.

The square root of 138909 is about 372.7049771602. The cubic root of 138909 is about 51.7897079079.

The spelling of 138909 in words is "one hundred thirty-eight thousand, nine hundred nine".