405865 has 4 divisors (see below), whose sum is σ = 487044. Its totient is φ = 324688.

The previous prime is 405863. The next prime is 405869. The reversal of 405865 is 568504.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 123904 + 281961 = 352^2 + 531^2 .

It is a cyclic number.

It is not a de Polignac number, because 405865 - 2¹ = 405863 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (405863) 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, 40582 + ... + 40591.

It is an arithmetic number, because the mean of its divisors is an integer number (121761).

2⁴⁰⁵⁸⁶⁵ is an apocalyptic number.

It is an amenable number.

405865 is a deficient number, since it is larger than the sum of its proper divisors (81179).

405865 is an equidigital number, since it uses as much as digits as its factorization.

405865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 81178.

The product of its (nonzero) digits is 4800, while the sum is 28.

The square root of 405865 is about 637.0753487618. The cubic root of 405865 is about 74.0389981927.

The spelling of 405865 in words is "four hundred five thousand, eight hundred sixty-five".