138631 has 4 divisors (see below), whose sum is σ = 139672. Its totient is φ = 137592.

The previous prime is 138629. The next prime is 138637. The reversal of 138631 is 136831.

138631 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, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 136831 = 293 ⋅467.

It is a cyclic number.

It is not a de Polignac number, because 138631 - 2¹ = 138629 is a prime.

It is a super-2 number, since 2×138631² = 38437108322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138637) 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, 285 + ... + 598.

It is an arithmetic number, because the mean of its divisors is an integer number (34918).

2¹³⁸⁶³¹ is an apocalyptic number.

138631 is a deficient number, since it is larger than the sum of its proper divisors (1041).

138631 is an equidigital number, since it uses as much as digits as its factorization.

138631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1040.

The product of its digits is 432, while the sum is 22.

The square root of 138631 is about 372.3318412384. The cubic root of 138631 is about 51.7551357440.

It can be divided in two parts, 138 and 631, that multiplied together give a palindrome (87078).

The spelling of 138631 in words is "one hundred thirty-eight thousand, six hundred thirty-one".