The 921s I'm used to are 18w, so you're in the neighborhood.
If you have a lot of problems with bulbs going out, you could buy some paddle style LEDs like these (hopefully the link works since I'm doing this on my phone):
Replaced all the 921s on my old trailer with the smaller 3w version (180 lumens), but the one I linked to is a 5w (300 lumens) which is more comparable with the normal 18w 921 (280 lumens). The 3w were obviously 60% less power hungry, but were also dimmer.
I never had one go out in about 3 years after that.