How to remove apostrophes and replace spaces with underscores?

Okay so for renaming files I got it setup like this: $replace($num(%track%,2)-$lower(%artist%)-$lower(%title%), ,_)
This will give me a file name like: 01-artist_name-file_name's_here.mp3
What is the code to give me: 01-artist_name-file_names_here.mp3

...
$replace($num(%track%,2)-$lower(%artist%)-$lower(%title%), ,_,'',)
the code to give: 01-artist_name-file_names_here.mp3

Thank you so much that did it!