PHP, 37 bytes

<?=substr_count(decbin($argn),1)%2<1;

To run it:

echo '<input>' | php -nF <filename>

Or Try it online!

Prints 1 for true, and nothing for false.

PHP, 37 36 bytes

<?=1&~substr_count(decbin($argn),1);

To run it:

echo '<input>' | php -nF <filename>

Or Try it online!

Prints 1 for true, and 0 for false.

-1 byte thanks to Benoit Esnard!