C4D has an upper limit of 16000 pixels in both directions, but a still image, at that size, will take a very long time to render, on a single machine.
Here is the link to a tutorial on setting up a "Tiled Camera" for rendering large stills, in C4D.
This tutorial shows you how to break a single-frame into "Tiles". Each tile can be rendered on a separate render-node, allowing multiple render-nodes to work in parallel, on all the tiles.
Not finding what you are looking for here? Try our searchable Help Resources or contact our support team for more information. You can always email firstname.lastname@example.org for technical questions. Don't hesitate to contact us - we are here to help you get your renders done and meet your deadlines.