138405 has 8 divisors (see below), whose sum is σ = 221472.
Its totient is φ = 73808.
The previous prime is 138403. The next prime is 138407. The reversal of 138405 is 504831.
Subtracting from 138405 its sum of digits (21), we obtain a square (138384 = 3722).
138405 = T4 + T5 + ... +
It is an interprime number because it is at equal distance from previous prime (138403) and next prime (138407).
It is a sphenic number, since it is the product of 3 distinct primes.
It is a cyclic number.
It is not a de Polignac number, because 138405 - 21 = 138403 is a prime.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (138401) 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, 4599 + ... + 4628.
It is an arithmetic number, because the mean of its divisors is an integer number (27684).
2138405 is an apocalyptic number.
138405 is a gapful number since it is divisible by the number (15) formed by its first and last digit.
It is an amenable number.
138405 is a deficient number, since it is larger than the sum of its proper divisors (83067).
138405 is an equidigital number, since it uses as much as digits as its factorization.
138405 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 9235.
The product of its (nonzero) digits is 480, while the sum is 21.
The square root of 138405 is about 372.0282247357.
The cubic root of 138405 is about 51.7269962405.
The spelling of 138405 in words is "one hundred thirty-eight thousand, four hundred five".