138399 has 4 divisors (see below), whose sum is σ = 184536. Its totient is φ = 92264.

The previous prime is 138389. The next prime is 138401. The reversal of 138399 is 993831.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 993831 = 3 ⋅331277.

It is a cyclic number.

It is not a de Polignac number, because 138399 - 2⁸ = 138143 is a prime.

It is a D-number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138319) 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, 23064 + ... + 23069.

It is an arithmetic number, because the mean of its divisors is an integer number (46134).

2¹³⁸³⁹⁹ is an apocalyptic number.

138399 is a deficient number, since it is larger than the sum of its proper divisors (46137).

138399 is an equidigital number, since it uses as much as digits as its factorization.

138399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46136.

The product of its digits is 5832, while the sum is 33.

The square root of 138399 is about 372.0201607440. The cubic root of 138399 is about 51.7262487568.

The spelling of 138399 in words is "one hundred thirty-eight thousand, three hundred ninety-nine".