138888861 has 32 divisors (see below), whose sum is σ = 203886720. Its totient is φ = 83736576.

The previous prime is 138888857. The next prime is 138888907. The reversal of 138888861 is 168888831.

It is a happy number.

It is not a de Polignac number, because 138888861 - 2² = 138888857 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138818861) 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 31 ways as a sum of consecutive naturals, for example, 167530 + ... + 168356.

It is an arithmetic number, because the mean of its divisors is an integer number (6371460).

Almost surely, 2^138888861 is an apocalyptic number.

It is an amenable number.

138888861 is a deficient number, since it is larger than the sum of its proper divisors (64997859).

138888861 is a wasteful number, since it uses less digits than its factorization.

138888861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 973.

The product of its digits is 589824, while the sum is 51.

The square root of 138888861 is about 11785.1118365504. Note that the first 3 decimals coincide. The cubic root of 138888861 is about 517.8720496627.

The spelling of 138888861 in words is "one hundred thirty-eight million, eight hundred eighty-eight thousand, eight hundred sixty-one".