509805 has 12 divisors (see below), whose sum is σ = 883740. Its totient is φ = 271872.

The previous prime is 509801. The next prime is 509833. The reversal of 509805 is 508905.

It can be written as a sum of positive squares in 2 ways, for example, as 181476 + 328329 = 426^2 + 573^2 .

It is not a de Polignac number, because 509805 - 2² = 509801 is a prime.

It is a super-2 number, since 2×509805² = 519802276050, which contains 22 as substring.

It is a Smith number, since the sum of its digits (27) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (509801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5620 + ... + 5709.

It is an arithmetic number, because the mean of its divisors is an integer number (73645).

2⁵⁰⁹⁸⁰⁵ is an apocalyptic number.

It is an amenable number.

509805 is a deficient number, since it is larger than the sum of its proper divisors (373935).

509805 is a wasteful number, since it uses less digits than its factorization.

509805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11340 (or 11337 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 27.

The square root of 509805 is about 714.0063024932. The cubic root of 509805 is about 79.8855133215.

Subtracting from 509805 its reverse (508905), we obtain a square (900 = 30²).

The spelling of 509805 in words is "five hundred nine thousand, eight hundred five".