138541028521 has 9 divisors (see below), whose sum is σ = 161163002871. Its totient is φ = 118747219752.

The previous prime is 138541028429. The next prime is 138541028531. The reversal of 138541028521 is 125820145831.

The square root of 138541028521 is 372211.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 82389091225 + 56151937296 = 287035^2 + 236964^2 .

It is not a de Polignac number, because 138541028521 - 2¹⁵ = 138540995753 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (138541028531) 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 8 ways as a sum of consecutive naturals, for example, 2578891 + ... + 2632063.

It is an arithmetic number, because the mean of its divisors is an integer number (17907000319).

Almost surely, 2^138541028521 is an apocalyptic number.

138541028521 is the 372211-st square number.

138541028521 is the 186106-th centered octagonal number.

It is an amenable number.

138541028521 is a deficient number, since it is larger than the sum of its proper divisors (22621974350).

138541028521 is an frugal number, since it uses more digits than its factorization.

138541028521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 106360 (or 53180 counting only the distinct ones).

The product of its (nonzero) digits is 76800, while the sum is 40.

The spelling of 138541028521 in words is "one hundred thirty-eight billion, five hundred forty-one million, twenty-eight thousand, five hundred twenty-one".