138661911 has 36 divisors (see below), whose sum is σ = 215514000. Its totient is φ = 85882368.

The previous prime is 138661909. The next prime is 138661921. The reversal of 138661911 is 119166831.

It is a happy number.

138661911 is a `hidden beast` number, since 1 + 38 + 6 + 619 + 1 + 1 = 666.

It is not a de Polignac number, because 138661911 - 2¹ = 138661909 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138661921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 231190 + ... + 231788.

It is an arithmetic number, because the mean of its divisors is an integer number (5986500).

Almost surely, 2^138661911 is an apocalyptic number.

138661911 is a deficient number, since it is larger than the sum of its proper divisors (76852089).

138661911 is a wasteful number, since it uses less digits than its factorization.

138661911 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 728 (or 708 counting only the distinct ones).

The product of its digits is 7776, while the sum is 36.

The square root of 138661911 is about 11775.4792259169. The cubic root of 138661911 is about 517.5898212780.

The spelling of 138661911 in words is "one hundred thirty-eight million, six hundred sixty-one thousand, nine hundred eleven".