138391 has 8 divisors (see below), whose sum is σ = 157824. Its totient is φ = 120120.

The previous prime is 138389. The next prime is 138401. The reversal of 138391 is 193831.

138391 = T₉₈ + T₉₉ + ... + T₁₂₀.

138391 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 138391 - 2¹ = 138389 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138311) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21 + ... + 526.

It is an arithmetic number, because the mean of its divisors is an integer number (19728).

2¹³⁸³⁹¹ is an apocalyptic number.

138391 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

138391 is a deficient number, since it is larger than the sum of its proper divisors (19433).

138391 is a wasteful number, since it uses less digits than its factorization.

138391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 581.

The product of its digits is 648, while the sum is 25.

The square root of 138391 is about 372.0094084832. The cubic root of 138391 is about 51.7252520782.

It can be divided in two parts, 138 and 391, that added together give a square (529 = 23²).

The spelling of 138391 in words is "one hundred thirty-eight thousand, three hundred ninety-one".