138555917361 has 45 divisors (see below), whose sum is σ = 210846943483. Its totient is φ = 90675471600.

The previous prime is 138555917359. The next prime is 138555917363. The reversal of 138555917361 is 163719555831.

It is a happy number.

The square root of 138555917361 is 372231.

It is a perfect power (a square), and thus also a powerful number.

138555917361 is a `hidden beast` number, since 1 + 3 + 85 + 559 + 1 + 7 + 3 + 6 + 1 = 666.

It is an interprime number because it is at equal distance from previous prime (138555917359) and next prime (138555917363).

It can be written as a sum of positive squares in only one way, i.e., 119495353761 + 19060563600 = 345681^2 + 138060^2 .

It is not a de Polignac number, because 138555917361 - 2¹ = 138555917359 is a prime.

It is a super-2 number, since 2×138555917361² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 138555917298 and 138555917307.

It is not an unprimeable number, because it can be changed into a prime (138555917363) by changing a digit.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 197654311 + ... + 197655011.

Almost surely, 2^138555917361 is an apocalyptic number.

138555917361 is the 372231-st square number.

138555917361 is the 186116-th centered octagonal number.

It is an amenable number.

138555917361 is a deficient number, since it is larger than the sum of its proper divisors (72291026122).

138555917361 is an frugal number, since it uses more digits than its factorization.

138555917361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1532 (or 763 counting only the distinct ones).

The product of its digits is 3402000, while the sum is 54.

The spelling of 138555917361 in words is "one hundred thirty-eight billion, five hundred fifty-five million, nine hundred seventeen thousand, three hundred sixty-one".