138155761 has 4 divisors (see below), whose sum is σ = 139035892. Its totient is φ = 137275632.

The previous prime is 138155749. The next prime is 138155767. The reversal of 138155761 is 167551831.

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 79923600 + 58232161 = 8940^2 + 7631^2 .

It is a cyclic number.

It is not a de Polignac number, because 138155761 - 2⁵ = 138155729 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 138155761.

It is not an unprimeable number, because it can be changed into a prime (138155767) 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 3 ways as a sum of consecutive naturals, for example, 439830 + ... + 440143.

It is an arithmetic number, because the mean of its divisors is an integer number (34758973).

Almost surely, 2^138155761 is an apocalyptic number.

It is an amenable number.

138155761 is a deficient number, since it is larger than the sum of its proper divisors (880131).

138155761 is an equidigital number, since it uses as much as digits as its factorization.

138155761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 880130.

The product of its digits is 25200, while the sum is 37.

The square root of 138155761 is about 11753.9678832299. The cubic root of 138155761 is about 516.9592768226.

The spelling of 138155761 in words is "one hundred thirty-eight million, one hundred fifty-five thousand, seven hundred sixty-one".