509689 has 2 divisors, whose sum is σ = 509690. Its totient is φ = 509688.

The previous prime is 509687. The next prime is 509693. The reversal of 509689 is 986905.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 291600 + 218089 = 540^2 + 467^2 .

It is a cyclic number.

It is not a de Polignac number, because 509689 - 2¹ = 509687 is a prime.

Together with 509687, it forms a pair of twin primes.

It is an Ulam number.

It is not a weakly prime, because it can be changed into another prime (509681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 254844 + 254845.

It is an arithmetic number, because the mean of its divisors is an integer number (254845).

2⁵⁰⁹⁶⁸⁹ is an apocalyptic number.

It is an amenable number.

509689 is a deficient number, since it is larger than the sum of its proper divisors (1).

509689 is an equidigital number, since it uses as much as digits as its factorization.

509689 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 19440, while the sum is 37.

The square root of 509689 is about 713.9250660959. The cubic root of 509689 is about 79.8794538658.

The spelling of 509689 in words is "five hundred nine thousand, six hundred eighty-nine".