This is the Coast Guard hull identification number from the starboard stern. The information at
http://www.boatsafe.com/nauticalknowhow/hin.htm will help you decode a date from this. The actual serial number is 216190 which should be stamped on the inside stems. See
http://forums.wcha.org/showthread.php?791 for more information about these numbers.
The Old Town canoe with serial number 216190 is a 16 foot long guide model with fiberglass in place of canvas, a full length stem band, a keel, and two painter rings. It was built between February and March, 1978. The original exterior paint color was green. It was shipped on May 5th, 1978 to Raleigh, North Carolina. A scan showing this build record can be found by following the link at the thumbnail image attached below.
This scan and several hundred thousand more were created with substantial grants from the Wooden Canoe Heritage Association (WCHA) and others. A description of the project to preserve these records is available at
http://www.wcha.org/ot_records/ if you want more details. I hope that you will join or renew your membership to the WCHA so that services like this can continue. See
http://www.wcha.org/about-the-wcha/ to learn more about the WCHA and
http://store.wcha.org/WCHA-New-Membership.html to join.
It is also possible that you could have another number or manufacturer if this description don't match the canoe. Feel free to reply here if you have any other questions.
Benson