- var_dump: documentation ( source)
- number_format: documentation ( source)
<?php
var_dump(number_format("",0));
var_dump(number_format(null,0));
var_dump(number_format(false,0));
var_dump(number_format('1234567890123456789',0));
var_dump(number_format((float)'1234567890123456789',0));