Postgresql RIGHT function giving an error

SELECT DISTINCT
    purchase_order_master.po1_num AS "PO #", 
    RIGHT(purchase_order_history.poh1_gl, 2) AS "Dept",
    purchase_order_history.poh1_gl,
    purchase_order_master.po1_podate AS "PO Date", 
    purchase_order_history.poh1_gl AS "GL Account #", 
    purchase_order_master.po1_dept, 
    purchase_order_master.po1_vname AS "Vendor Name", 
    purchase_order_master.po1_vnum AS "Vendor Number"
    
FROM
    purchase_order_master
    INNER JOIN
    purchase_order_line_items
    ON 
        purchase_order_master.po1_num = purchase_order_line_items.po2_num AND
        purchase_order_master.po1_arid = purchase_order_line_items.po2_arid
    INNER JOIN
    purchase_order_history
    ON 
        purchase_order_line_items.po2_num = purchase_order_history.poh1_ponum AND
        purchase_order_line_items.po2_arid = purchase_order_history.poh1_arid
ORDER BY
 "PO Date" DESC;

Gives error:

ERROR: function right(numeric, integer) does not exist LINE 3: RIGHT(purchase_order_history.poh1_gl, 2) AS Dept, ^ HINT: No function matches the given name and argument types. You might need to add explicit type >casts.

Do I need to change the column values before I try?