809605 has 4 divisors (see below), whose sum is σ = 971532. Its totient is φ = 647680.

The previous prime is 809603. The next prime is 809629. The reversal of 809605 is 506908.

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 88804 + 720801 = 298^2 + 849^2 .

It is not a de Polignac number, because 809605 - 2¹ = 809603 is a prime.

It is a Duffinian number.

809605 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (809603) 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, 80956 + ... + 80965.

It is an arithmetic number, because the mean of its divisors is an integer number (242883).

2⁸⁰⁹⁶⁰⁵ is an apocalyptic number.

It is an amenable number.

809605 is a deficient number, since it is larger than the sum of its proper divisors (161927).

809605 is a wasteful number, since it uses less digits than its factorization.

809605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161926.

The product of its (nonzero) digits is 2160, while the sum is 28.

The square root of 809605 is about 899.7805287958. The cubic root of 809605 is about 93.2018201613.

The spelling of 809605 in words is "eight hundred nine thousand, six hundred five".