How to get the Page Number of the Current Page in Single Post Pagination
For your single page, you could try using the global $page variable. Another alternative would be to try fetching the query page variable, with e.g.: $wpse_current_page = (int) get_query_var( ‘page’ ); if( $wpse_current_page > 0 ) { printf( __( ‘Page Number: %d’, ‘wpse-theme-slug’ ), (int) $wpse_current_page ); } on your single page.