509861 has 4 divisors (see below), whose sum is σ = 556224. Its totient is φ = 463500.

The previous prime is 509843. The next prime is 509863. The reversal of 509861 is 168905.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 509861 - 2⁶ = 509797 is a prime.

It is a super-3 number, since 3×509861³ = 397627703575333143, which contains 333 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 509861.

It is not an unprimeable number, because it can be changed into a prime (509863) 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, 23165 + ... + 23186.

It is an arithmetic number, because the mean of its divisors is an integer number (139056).

2⁵⁰⁹⁸⁶¹ is an apocalyptic number.

It is an amenable number.

509861 is a deficient number, since it is larger than the sum of its proper divisors (46363).

509861 is a wasteful number, since it uses less digits than its factorization.

509861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46362.

The product of its (nonzero) digits is 2160, while the sum is 29.

The square root of 509861 is about 714.0455167565. The cubic root of 509861 is about 79.8884382470. Note that the first 3 decimals are identical.

The spelling of 509861 in words is "five hundred nine thousand, eight hundred sixty-one".