As today's offer is for Aplus File Splitter and ReJoiner, plus with alternatives suggested in the comments, wanted to post a quick reminder that splitting files isn't just something you used to do back in the days of floppy disks. ;)
A portion of an encrypted zip or 7-zipped file is more useless than the encrypted original should someone get access to it. If you're worried about storing something in the cloud, store pieces of it on separate services. For someone to get the full file they'd have to know which accounts you used & break into each, know which files went together, how to piece them together, & then beat the encryption.