138136261 has 4 divisors (see below), whose sum is σ = 139063500. Its totient is φ = 137209024.

The previous prime is 138136247. The next prime is 138136267. The reversal of 138136261 is 162631831.

138136261 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 162631831 = 2879 ⋅56489.

It can be written as a sum of positive squares in 2 ways, for example, as 31013761 + 107122500 = 5569^2 + 10350^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-138136261 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138136267) 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, 463396 + ... + 463693.

It is an arithmetic number, because the mean of its divisors is an integer number (34765875).

Almost surely, 2^138136261 is an apocalyptic number.

It is an amenable number.

138136261 is a deficient number, since it is larger than the sum of its proper divisors (927239).

138136261 is an equidigital number, since it uses as much as digits as its factorization.

138136261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 927238.

The product of its digits is 5184, while the sum is 31.

The square root of 138136261 is about 11753.1383468417. The cubic root of 138136261 is about 516.9349535995.

The spelling of 138136261 in words is "one hundred thirty-eight million, one hundred thirty-six thousand, two hundred sixty-one".