6405 has 16 divisors (see below), whose sum is σ = 11904.
Its totient is φ = 2880.
The previous prime is 6397. The next prime is 6421. The reversal of 6405 is 5046.
It is not a de Polignac number, because 6405 - 23 = 6397 is a prime.
It is a Harshad number since it is a multiple of its sum of digits (15).
It is a congruent number.
It is an unprimeable number.
It is a pernicious number, because its binary representation contains a prime number (5) of ones.
It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 75 + ... + 135.
It is an arithmetic number, because the mean of its divisors is an integer number (744).
It is an amenable number.
6405 is a deficient number, since it is larger than the sum of its proper divisors (5499).
6405 is a wasteful number, since it uses less digits than its factorization.
6405 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 76.
The product of its (nonzero) digits is 120, while the sum is 15.
The square root of 6405 is about 80.0312438989.
The cubic root of 6405 is about 18.5711890643.
The spelling of 6405 in words is "six thousand, four hundred five".