138439321 has 4 divisors (see below), whose sum is σ = 138481252. Its totient is φ = 138397392.

The previous prime is 138439309. The next prime is 138439333. The reversal of 138439321 is 123934831.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 123934831 = 71 ⋅1745561.

It is an interprime number because it is at equal distance from previous prime (138439309) and next prime (138439333).

It can be written as a sum of positive squares in 2 ways, for example, as 29550096 + 108889225 = 5436^2 + 10435^2 .

It is a cyclic number.

It is not a de Polignac number, because 138439321 - 2²¹ = 136342169 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (138439391) 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, 15546 + ... + 22771.

It is an arithmetic number, because the mean of its divisors is an integer number (34620313).

Almost surely, 2^138439321 is an apocalyptic number.

It is an amenable number.

138439321 is a deficient number, since it is larger than the sum of its proper divisors (41931).

138439321 is an equidigital number, since it uses as much as digits as its factorization.

138439321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41930.

The product of its digits is 15552, while the sum is 34.

The square root of 138439321 is about 11766.0240098344. The cubic root of 138439321 is about 517.3127155695.

The spelling of 138439321 in words is "one hundred thirty-eight million, four hundred thirty-nine thousand, three hundred twenty-one".