Artikelnummer anzeigen lassen /Item number display

There is no option for that.

For the product page, you can do as explained here:
www.hikashop.com/en/support/documentatio...ng.html#product_code
For the shopping cart module, you will have to edit the file "cart" of the views "checkout" and "product" via the menu Display->views and add some code like that:
<?php echo $row->product_code; ?>

after:
<?php echo $row->product_name; ?>

For the emails, you need to edit them via the menu System->Emails (Business edition only) in a similar manner by adding :
<?php echo $item->order_product_code; ?>

after:
<?php echo $item->order_product_name; ?>