405905 has 4 divisors (see below), whose sum is σ = 487092. Its totient is φ = 324720.

The previous prime is 405901. The next prime is 405917. The reversal of 405905 is 509504.

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 201601 + 204304 = 449^2 + 452^2 .

It is not a de Polignac number, because 405905 - 2² = 405901 is a prime.

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 405905.

It is not an unprimeable number, because it can be changed into a prime (405901) 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, 40586 + ... + 40595.

It is an arithmetic number, because the mean of its divisors is an integer number (121773).

2⁴⁰⁵⁹⁰⁵ is an apocalyptic number.

It is an amenable number.

405905 is a deficient number, since it is larger than the sum of its proper divisors (81187).

405905 is an equidigital number, since it uses as much as digits as its factorization.

405905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81186.

The product of its (nonzero) digits is 900, while the sum is 23.

The square root of 405905 is about 637.1067414492. The cubic root of 405905 is about 74.0414304158.

The spelling of 405905 in words is "four hundred five thousand, nine hundred five".