In this task, you are given an input list A. You need to find all the elements of the list that are numbers and calculate their sum.
['1583', 'w', 'A', '5971', 'L', 'L', '3421', '4271', '7033', 'B', '5987', 'I', 'v', 'H', '9069', '4845', 'G', 'S', 'd', 'O']