You can use an app like
Photo exif editor, but that only edits the EXIF date, not the modified date you see in a file manager. (To do that you have to "touch" the file, and I don't believe anyone's written touch for Android. (Copying the file, for instance, would modify the copy, so it would have the current date.)
If you mean printed ON the picture,
APD TimeStamp will do that.