138840 has 64 divisors (see below), whose sum is σ = 453600. Its totient is φ = 33792.

The previous prime is 138829. The next prime is 138841. The reversal of 138840 is 48831.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 138840.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138841) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1516 + ... + 1604.

2¹³⁸⁸⁴⁰ is an apocalyptic number.

138840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 138840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (226800).

138840 is an abundant number, since it is smaller than the sum of its proper divisors (314760).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

138840 is a wasteful number, since it uses less digits than its factorization.

138840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 116 (or 112 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 24.

The square root of 138840 is about 372.6123991496. The cubic root of 138840 is about 51.7811313537.

Subtracting from 138840 its reverse (48831), we obtain a palindrome (90009).

The spelling of 138840 in words is "one hundred thirty-eight thousand, eight hundred forty".