509871 has 4 divisors (see below), whose sum is σ = 679832. Its totient is φ = 339912.

The previous prime is 509867. The next prime is 509879. The reversal of 509871 is 178905.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 509871 - 2² = 509867 is a prime.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (509879) 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, 84976 + ... + 84981.

It is an arithmetic number, because the mean of its divisors is an integer number (169958).

2⁵⁰⁹⁸⁷¹ is an apocalyptic number.

509871 is a deficient number, since it is larger than the sum of its proper divisors (169961).

509871 is a wasteful number, since it uses less digits than its factorization.

509871 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 169960.

The product of its (nonzero) digits is 2520, while the sum is 30.

The square root of 509871 is about 714.0525190769. The cubic root of 509871 is about 79.8889605326. Note that the first 3 decimals are identical.

The spelling of 509871 in words is "five hundred nine thousand, eight hundred seventy-one".