Cognomen 衍寅 (衍寅 
) , in the entire world, is a very rare surname. The surname 衍寅 is habitual in Eastern Asia, particularly China, where it is an extremely rare surname. More prevalently, 衍寅 is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| 衍寅 | China |