138231557 has 2 divisors, whose sum is σ = 138231558. Its totient is φ = 138231556.

The previous prime is 138231553. The next prime is 138231563. The reversal of 138231557 is 755132831.

138231557 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 119990116 + 18241441 = 10954^2 + 4271^2 .

It is an emirp because it is prime and its reverse (755132831) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 138231557 - 2² = 138231553 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (138231553) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69115778 + 69115779.

It is an arithmetic number, because the mean of its divisors is an integer number (69115779).

Almost surely, 2^138231557 is an apocalyptic number.

It is an amenable number.

138231557 is a deficient number, since it is larger than the sum of its proper divisors (1).

138231557 is an equidigital number, since it uses as much as digits as its factorization.

138231557 is an evil number, because the sum of its binary digits is even.

The product of its digits is 25200, while the sum is 35.

The square root of 138231557 is about 11757.1917140106. The cubic root of 138231557 is about 517.0537988354.

The spelling of 138231557 in words is "one hundred thirty-eight million, two hundred thirty-one thousand, five hundred fifty-seven".