138645757 has 4 divisors (see below), whose sum is σ = 138669340. Its totient is φ = 138622176.

The previous prime is 138645743. The next prime is 138645769. The reversal of 138645757 is 757546831.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 757546831 = 20051 ⋅37781.

It can be written as a sum of positive squares in 2 ways, for example, as 27258841 + 111386916 = 5221^2 + 10554^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-138645757 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 (138645707) 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, 4969 + ... + 17377.

It is an arithmetic number, because the mean of its divisors is an integer number (34667335).

Almost surely, 2^138645757 is an apocalyptic number.

It is an amenable number.

138645757 is a deficient number, since it is larger than the sum of its proper divisors (23583).

138645757 is a wasteful number, since it uses less digits than its factorization.

138645757 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23582.

The product of its digits is 705600, while the sum is 46.

The square root of 138645757 is about 11774.7932890561. The cubic root of 138645757 is about 517.5697208995.

The spelling of 138645757 in words is "one hundred thirty-eight million, six hundred forty-five thousand, seven hundred fifty-seven".