Xiao Li processed a batch of parts. After processing 180 parts, he improved the work efficiency by 20% and completed the remaining tasks. As a result, he completed the task 4 days ahead of schedule. If Xiao Li improves work efficiency by 35% from the very beginning, he can finish the task 7 days ahead of time by processing this batch of parts. How many parts are there in total?
小李加工一批零件，加工了180个后，将工效提高20%完成余下的任务，结果提前4天完成任务．如果小李一开始就将工效提高35%，加工这批零件就能提前7天完成任务．求这批零件一共有多少个？
<result>1_620</result>