21:23 Written.
The words "written" or "in writing" may include printing or any other mode of representing words and letters, except where the written signature of a person is required. The signature of any corporate officer upon a corporate bond or other corporate obligation for the payment of money, or upon any interest coupons attached thereto, may be a facsimile, engraved or printed, where such bond or other obligation is authenticated or certified by a trustee.