8405 has 6 divisors (see below), whose sum is σ = 10338. Its totient is φ = 6560.

The previous prime is 8389. The next prime is 8419. The reversal of 8405 is 5048.

It can be written as a sum of positive squares in 3 ways, for example, as 484 + 7921 = 22^2 + 89^2 .

It is not a de Polignac number, because 8405 - 2⁴ = 8389 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a plaindrome in base 7 and base 9.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 185 + ... + 225.

It is an arithmetic number, because the mean of its divisors is an integer number (1723).

2⁸⁴⁰⁵ is an apocalyptic number.

It is an amenable number.

8405 is a deficient number, since it is larger than the sum of its proper divisors (1933).

8405 is an equidigital number, since it uses as much as digits as its factorization.

8405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87 (or 46 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 8405 is about 91.6787870775. The cubic root of 8405 is about 20.3319596552.

It can be divided in two parts, 8 and 405, that multiplied together give a triangular number (3240 = T₈₀).

The spelling of 8405 in words is "eight thousand, four hundred five".