138721165 has 16 divisors (see below), whose sum is σ = 189495936. Its totient is φ = 96500800.

The previous prime is 138721159. The next prime is 138721169. The reversal of 138721165 is 561127831.

It is a happy number.

It is not a de Polignac number, because 138721165 - 2³ = 138721157 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 138721165.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138721169) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 53566 + ... + 56095.

It is an arithmetic number, because the mean of its divisors is an integer number (11843496).

Almost surely, 2^138721165 is an apocalyptic number.

It is an amenable number.

138721165 is a deficient number, since it is larger than the sum of its proper divisors (50774771).

138721165 is a wasteful number, since it uses less digits than its factorization.

138721165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 109700.

The product of its digits is 10080, while the sum is 34.

The square root of 138721165 is about 11777.9949482074. The cubic root of 138721165 is about 517.6635375074.

Adding to 138721165 its reverse (561127831), we get a palindrome (699848996).

The spelling of 138721165 in words is "one hundred thirty-eight million, seven hundred twenty-one thousand, one hundred sixty-five".