I recently had to print a large format canvas, and I noticed the printing company understood inches and DPI (dots-per-inch) but it did not understand megapixels. They told me: your 4000 x 4000px image is too small, but they could not tell me how big it had to be.
So I made a calculator for it: if you want to print a canvas of 60x60cm (23.6×23.6 inch) at 300 dpi with a bleed of 2mm, you need a 7134 px x 7134 px image (+- 51 megapixel)
Given the fact that most digital cameras do not have that resolution, this probably means you will have to ‘upsize’ your source image. For some background on that, read http://blog.forret.com/2006/08/23/how-to-upsize-an-image/