Just to be clear, you're talking about one single photo and not the whole folder of photos equalling that 1.86gb, right? You've never stated what file type it was. Can't really provide answer without knowing the file type. Files of that size to pop out of cameras are mostly multiple exposure or long exposure, stuff like panorama or combined multi-exposures as it stacks data on data to form one large file.
Do you really need to print that large? That's pretty much aiming for a Billboard on the streets.