138666831 has 4 divisors (see below), whose sum is σ = 184889112. Its totient is φ = 92444552.

The previous prime is 138666811. The next prime is 138666859.

138666831 is nontrivially palindromic in base 10.

138666831 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 138666831 - 2⁵ = 138666799 is a prime.

It is a super-2 number, since 2×138666831² = 38456980039165122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138666811) 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, 23111136 + ... + 23111141.

It is an arithmetic number, because the mean of its divisors is an integer number (46222278).

Almost surely, 2^138666831 is an apocalyptic number.

138666831 is a deficient number, since it is larger than the sum of its proper divisors (46222281).

138666831 is an equidigital number, since it uses as much as digits as its factorization.

138666831 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46222280.

The product of its digits is 124416, while the sum is 42.

The square root of 138666831 is about 11775.6881327590. The cubic root of 138666831 is about 517.5959429106.

The spelling of 138666831 in words is "one hundred thirty-eight million, six hundred sixty-six thousand, eight hundred thirty-one".