<?php

function get_full_hour($input) {

	if (! is_int($input)) return;


    $hours = floor($input / 3600);
    $mins = floor(($input - ($hours * 3600)) / 60);
    $secs = floor($input % 60);

    return sprintf('%02s:%02s:%02s', $hours, $mins, $secs);
}


echo get_full_hour(28 * 3600);