138931381 has 4 divisors (see below), whose sum is σ = 139007200. Its totient is φ = 138855564.

The previous prime is 138931369. The next prime is 138931399. The reversal of 138931381 is 183139831.

It is a happy number.

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.

It is a cyclic number.

It is not a de Polignac number, because 138931381 - 2¹¹ = 138929333 is a prime.

It is a super-2 number, since 2×138931381² = 38603857253134322, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 138931381.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138931301) 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, 35091 + ... + 38848.

It is an arithmetic number, because the mean of its divisors is an integer number (34751800).

Almost surely, 2^138931381 is an apocalyptic number.

It is an amenable number.

138931381 is a deficient number, since it is larger than the sum of its proper divisors (75819).

138931381 is an equidigital number, since it uses as much as digits as its factorization.

138931381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 75818.

The product of its digits is 15552, while the sum is 37.

The square root of 138931381 is about 11786.9156695040. The cubic root of 138931381 is about 517.9248920882.

The spelling of 138931381 in words is "one hundred thirty-eight million, nine hundred thirty-one thousand, three hundred eighty-one".