138990 has 32 divisors (see below), whose sum is σ = 344736. Its totient is φ = 35840.

The previous prime is 138977. The next prime is 139021. The reversal of 138990 is 99831.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

138990 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1174 + ... + 1286.

It is an arithmetic number, because the mean of its divisors is an integer number (10773).

2¹³⁸⁹⁹⁰ is an apocalyptic number.

138990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 138990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (172368).

138990 is an abundant number, since it is smaller than the sum of its proper divisors (205746).

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

138990 is a wasteful number, since it uses less digits than its factorization.

138990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 164.

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

The square root of 138990 is about 372.8136263604. The cubic root of 138990 is about 51.7997724134.

It can be divided in two parts, 138 and 990, that added together give a triangular number (1128 = T₄₇).

The spelling of 138990 in words is "one hundred thirty-eight thousand, nine hundred ninety".