138444121 has 4 divisors (see below), whose sum is σ = 142185892. Its totient is φ = 134702352.

The previous prime is 138444091. The next prime is 138444143. The reversal of 138444121 is 121444831.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 117614025 + 20830096 = 10845^2 + 4564^2 .

It is a cyclic number.

It is not a de Polignac number, because 138444121 - 2⁷ = 138443993 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 138444121.

It is not an unprimeable number, because it can be changed into a prime (138444181) 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, 1870830 + ... + 1870903.

It is an arithmetic number, because the mean of its divisors is an integer number (35546473).

Almost surely, 2^138444121 is an apocalyptic number.

It is an amenable number.

138444121 is a deficient number, since it is larger than the sum of its proper divisors (3741771).

138444121 is an equidigital number, since it uses as much as digits as its factorization.

138444121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3741770.

The product of its digits is 3072, while the sum is 28.

The square root of 138444121 is about 11766.2279852126. The cubic root of 138444121 is about 517.3186942955.

Adding to 138444121 its reverse (121444831), we get a palindrome (259888952).

The spelling of 138444121 in words is "one hundred thirty-eight million, four hundred forty-four thousand, one hundred twenty-one".