509840 has 20 divisors (see below), whose sum is σ = 1185564. Its totient is φ = 203904.

The previous prime is 509837. The next prime is 509843. The reversal of 509840 is 48905.

It is an interprime number because it is at equal distance from previous prime (509837) and next prime (509843).

It can be written as a sum of positive squares in 2 ways, for example, as 309136 + 200704 = 556^2 + 448^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a hoax number, since the sum of its digits (26) coincides with the sum of the digits of its distinct prime factors.

It is an Ulam number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 509840.

It is not an unprimeable number, because it can be changed into a prime (509843) 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, 3107 + ... + 3266.

2⁵⁰⁹⁸⁴⁰ is an apocalyptic number.

It is an amenable number.

509840 is an abundant number, since it is smaller than the sum of its proper divisors (675724).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

509840 is a wasteful number, since it uses less digits than its factorization.

509840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6386 (or 6380 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 26.

The square root of 509840 is about 714.0308116601. The cubic root of 509840 is about 79.8873414250.

The spelling of 509840 in words is "five hundred nine thousand, eight hundred forty".