Photoshop, as Kallikru, will do the job and you can transfer it to CMYK.

However, this is important to remember: CMYK will wash your colors out, so you may have to compensate and add some saturation. I find that if I saturate about nine percent, I'll get as close as possible to the RGB version. You never really do have the same result with CMYK, because it never looks as vibrant and luminescent as RGB does. Cyan in particular looks flat, and reds tend to go orangey, so you might want to slide your reds over to the blue a little to compensate. It is one of my pet peeves about large scale printing, I think CMYK is mud next to RGB, and I cannot fathom why they don't standardize printing to RGB.

Best of luck to you :)