138166881178 has 4 divisors (see below), whose sum is σ = 207250321770. Its totient is φ = 69083440588.

The previous prime is 138166881143. The next prime is 138166881191. The reversal of 138166881178 is 871188661831.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 81811444729 + 56355436449 = 286027^2 + 237393^2 .

It is a Smith number, since the sum of its digits (58) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 34541720293 + ... + 34541720296.

Almost surely, 2^138166881178 is an apocalyptic number.

138166881178 is a deficient number, since it is larger than the sum of its proper divisors (69083440592).

138166881178 is an equidigital number, since it uses as much as digits as its factorization.

138166881178 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69083440591.

The product of its digits is 3096576, while the sum is 58.

The spelling of 138166881178 in words is "one hundred thirty-eight billion, one hundred sixty-six million, eight hundred eighty-one thousand, one hundred seventy-eight".