So glad to see everything still going smoothly here, I haven't been on in forever. You guys have helped me immensely in my coin collecting journey, and I thank you all.

Now, I have a quick question for the bill collectors here, since I know very little. I found a $20 bill in my register today, series 1974. I know that's not really very old, but it's in unusually good condition. I wouldn't say 'perfect,' but if it were a coin I would grade it AU58-AU59

Obviously, my question is, is it worth anything? And more importantly, is it worth keeping as a long term thing? I hate to just spend it cause, I mean, you don't see many bills in this good shape in the wild that aren't new.
Thanks!
Oh, and the serial # is K 90800800 A if that makes any difference.