509823 has 12 divisors (see below), whose sum is σ = 756808. Its totient is φ = 330480.

The previous prime is 509801. The next prime is 509833. The reversal of 509823 is 328905.

It is not a de Polignac number, because 509823 - 2¹⁰ = 508799 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (509833) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 433 + ... + 1098.

2⁵⁰⁹⁸²³ is an apocalyptic number.

509823 is a deficient number, since it is larger than the sum of its proper divisors (246985).

509823 is a wasteful number, since it uses less digits than its factorization.

509823 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1574 (or 1571 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 509823 is about 714.0189073127. The cubic root of 509823 is about 79.8864534995.

Subtracting from 509823 its sum of digits (27), we obtain a square (509796 = 714²).

The spelling of 509823 in words is "five hundred nine thousand, eight hundred twenty-three".