VBA - Creating a macro for reducing text in cell

Sub t()
Dim i As Long
    With ActiveSheet
        If .Range("A2").Value <> "" Then .Range("N2").Value = "N"
        For i = 2 To .Cells.Find("*", , xlValues, xlPart, xlByRows, xlPrevious).Row
            .Cells(i, 2) = Format(.Cells(i, 2).Value, "yyyymmdd")
            .Cells(i, 2).NumberFormat = "General"
            .Cells(i, 21) = Format(.Cells(i, 21).Value, "Hh:mm:ss")
        Next
    End With
End Sub