jonny1,

Note that AA_EXP09's profile indicates he is from Vancouver (in Canada). His bank will accept the $20 coins for deposit, and/or exchange them for $20 bills. It's legal tender in Canada, so, could be used as one would use a $20 bill (in truth not the best use of it however).

That said, it is doubtful you will have much success depositing an uncommon Canadian coin into a bank outside of Canada.

EDIT: I see Doc Savage already beat me to the comment.