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.
['E', 'p', '4735', '9311', '9577', '407', 'y', 'Q', '1439', '9149', 'Q', '6041', '2119', '3359', '2823', 'i', '55', '5435', '6909']