select my_number
          , cast(concat(substr(my_number,2,5), '00000')   AS UNSIGNED INTEGER)
          , cast( my_number, AS UNSIGNED INTEGER) +
                     cast(concat(substr(my_number,2,5), '00000')   AS UNSIGNED INTEGER)
      from my_table

select cast(col as bigint) + cast(substr(col, 2, 5) || '00000' as bigint)