405665 has 12 divisors (see below), whose sum is σ = 530964. Its totient is φ = 295776.

The previous prime is 405659. The next prime is 405667. The reversal of 405665 is 566504.

It can be written as a sum of positive squares in 2 ways, for example, as 99856 + 305809 = 316^2 + 553^2 .

It is not a de Polignac number, because 405665 - 2¹⁶ = 340129 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 405665.

It is not an unprimeable number, because it can be changed into a prime (405667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5096 + ... + 5174.

It is an arithmetic number, because the mean of its divisors is an integer number (44247).

2⁴⁰⁵⁶⁶⁵ is an apocalyptic number.

It is an amenable number.

405665 is a deficient number, since it is larger than the sum of its proper divisors (125299).

405665 is an equidigital number, since it uses as much as digits as its factorization.

405665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 176 (or 97 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 26.

The square root of 405665 is about 636.9183621156. The cubic root of 405665 is about 74.0268346797.

The spelling of 405665 in words is "four hundred five thousand, six hundred sixty-five".