138181817 has 4 divisors (see below), whose sum is σ = 138205440. Its totient is φ = 138158196.

The previous prime is 138181811. The next prime is 138181829. The reversal of 138181817 is 718181831.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 138181817 - 2⁴ = 138181801 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (138181811) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4184 + ... + 17142.

It is an arithmetic number, because the mean of its divisors is an integer number (34551360).

Almost surely, 2^138181817 is an apocalyptic number.

It is an amenable number.

138181817 is a deficient number, since it is larger than the sum of its proper divisors (23623).

138181817 is a wasteful number, since it uses less digits than its factorization.

138181817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23622.

The product of its digits is 10752, while the sum is 38.

The square root of 138181817 is about 11755.0762226368. The cubic root of 138181817 is about 516.9917740661.

The spelling of 138181817 in words is "one hundred thirty-eight million, one hundred eighty-one thousand, eight hundred seventeen".