509665 has 8 divisors (see below), whose sum is σ = 658728. Its totient is φ = 376320.

The previous prime is 509659. The next prime is 509681. The reversal of 509665 is 566905.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 1296 + 508369 = 36^2 + 713^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 509665 - 2⁵ = 509633 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3856 + ... + 3985.

It is an arithmetic number, because the mean of its divisors is an integer number (82341).

2⁵⁰⁹⁶⁶⁵ is an apocalyptic number.

It is an amenable number.

509665 is a deficient number, since it is larger than the sum of its proper divisors (149063).

509665 is a wasteful number, since it uses less digits than its factorization.

509665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7859.

The product of its (nonzero) digits is 8100, while the sum is 31.

The square root of 509665 is about 713.9082574113. The cubic root of 509665 is about 79.8782000705.

The spelling of 509665 in words is "five hundred nine thousand, six hundred sixty-five".