138791381557 has 2 divisors, whose sum is σ = 138791381558. Its totient is φ = 138791381556.

The previous prime is 138791381513. The next prime is 138791381569. The reversal of 138791381557 is 755183197831.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 120519371281 + 18272010276 = 347159^2 + 135174^2 .

It is an emirp because it is prime and its reverse (755183197831) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 138791381557 - 2¹⁹ = 138790857269 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (138791381257) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69395690778 + 69395690779.

It is an arithmetic number, because the mean of its divisors is an integer number (69395690779).

Almost surely, 2^138791381557 is an apocalyptic number.

It is an amenable number.

138791381557 is a deficient number, since it is larger than the sum of its proper divisors (1).

138791381557 is an equidigital number, since it uses as much as digits as its factorization.

138791381557 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6350400, while the sum is 58.

The spelling of 138791381557 in words is "one hundred thirty-eight billion, seven hundred ninety-one million, three hundred eighty-one thousand, five hundred fifty-seven".