13: There are 16 subsets * *, including the first kind of empty sets, the second kind of single element sets {1}, {2}, {3}, {4}, and the third kind of binary sets {1, 2} and {650}. 3}, {1, 2, 4}, {1, 3, 4}, {2, 3, 4}, and the quaternary set of the fifth kind {1, 2, 3, 4} is a given set; Proper subset 15, excluding the fifth category, namely the given set; Excluding the first and fifth categories, there are 14 non-empty proper subset.