138421 has 4 divisors (see below), whose sum is σ = 139500. Its totient is φ = 137344.

The previous prime is 138407. The next prime is 138427. The reversal of 138421 is 124831.

138421 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 8100 + 130321 = 90^2 + 361^2 .

It is a cyclic number.

It is not a de Polignac number, because 138421 - 2⁵ = 138389 is a prime.

It is a Duffinian number.

138421 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138427) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 316 + ... + 613.

It is an arithmetic number, because the mean of its divisors is an integer number (34875).

2¹³⁸⁴²¹ is an apocalyptic number.

It is an amenable number.

138421 is a deficient number, since it is larger than the sum of its proper divisors (1079).

138421 is an equidigital number, since it uses as much as digits as its factorization.

138421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1078.

The product of its digits is 192, while the sum is 19.

The square root of 138421 is about 372.0497278591. The cubic root of 138421 is about 51.7289894249.

The spelling of 138421 in words is "one hundred thirty-eight thousand, four hundred twenty-one".