138440 has 16 divisors (see below), whose sum is σ = 311580. Its totient is φ = 55360.

The previous prime is 138433. The next prime is 138449. The reversal of 138440 is 44831.

It can be written as a sum of positive squares in 2 ways, for example, as 131044 + 7396 = 362^2 + 86^2 .

It is a Harshad number since it is a multiple of its sum of digits (20).

It is not an unprimeable number, because it can be changed into a prime (138449) by changing a digit.

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, 1691 + ... + 1770.

2¹³⁸⁴⁴⁰ is an apocalyptic number.

138440 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

138440 is an abundant number, since it is smaller than the sum of its proper divisors (173140).

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

138440 is a wasteful number, since it uses less digits than its factorization.

138440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3472 (or 3468 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 20.

The square root of 138440 is about 372.0752612040. The cubic root of 138440 is about 51.7313561318.

The spelling of 138440 in words is "one hundred thirty-eight thousand, four hundred forty".