u/bluishverses

Hello. I have a scanned textbook pdf consisting of about 180 pages, but each page actually contains two pages. So, the textbook actually has the double amount of pages its pdf version has because it was scanned that way. I was wondering whether there was a way (online, freeware...) to split those pages? Is it possible to make a pdf that has 360 pages instead of 180? Thank you!