138021 has 8 divisors (see below), whose sum is σ = 198240. Its totient is φ = 84912.

The previous prime is 138007. The next prime is 138041. The reversal of 138021 is 120831.

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 138021 - 2⁶ = 137957 is a prime.

It is a Curzon number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 138021.

It is not an unprimeable number, because it can be changed into a prime (138041) 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, 1731 + ... + 1808.

It is an arithmetic number, because the mean of its divisors is an integer number (24780).

2¹³⁸⁰²¹ is an apocalyptic number.

It is an amenable number.

138021 is a deficient number, since it is larger than the sum of its proper divisors (60219).

138021 is a wasteful number, since it uses less digits than its factorization.

138021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3555.

The product of its (nonzero) digits is 48, while the sum is 15.

The square root of 138021 is about 371.5117763948. The cubic root of 138021 is about 51.6791136620.

Adding to 138021 its reverse (120831), we get a palindrome (258852).

The spelling of 138021 in words is "one hundred thirty-eight thousand, twenty-one".