How do I add commas to these numbers?

[Gutspiller]

I have this on my front page:

PHP Code:

<?
$last24 = time() - 0;
$threads = $DB_site->fetch_array($DB_site->query("SELECT COUNT(*) as total FROM thread WHERE lastpost < $last24 AND (forumid = '143' OR forumid = '162' OR forumid = '161' OR forumid = '163' OR forumid = '145' OR forumid = '153' OR forumid = '164' OR forumid = '155' OR forumid = '167' OR forumid = '158' OR forumid = '165' OR forumid = '166' OR forumid = '127')"));
echo $threads[total];
?>

It grabs how many total threads I have in all those forums. I want the total number displayed though to have a comma intween every three digits so when it shows 11000 it shows 11,000.

Can somebody please help me with this little hackie thingie? I would really appreciate any help somebody can provide.

Thanks.