What is the graphic design term for page number?

Pagination (The numbering to individual pages in a multi-page document)

Explanation:

Pagination is the process of separating print or digital content into discrete pages.

Pagination is the process of separating print documents or digital content that can be used online into discrete pages, and you assign numbers to each page of the print document.

However, in the print industry (graphics designing) and for some online contents such as landing pages, etc, pagination refers to the automated process of adding consecutive numbers to identify the sequential order of pages in a multi-page document.

Pagination is essential for magazines and brochures, as magazine and brochure's pages position are important when printing such documents.

Example of Pagination tools in daily life

You can do pagination using Adobe Illustrator, Adobe InDesign, and other graphic designing tools that handle the multi-page document.