Cognomen Allagappan (Allagappan 
) , in the entire world, is a very rare family name. The cognomen Allagappan is habitual in Malaysia, where it is a rare surname, Singapore, and India, where it is an extremely rare surname. Very seldom, Allagappan is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Allagappan | United Kingdom, India, Malaysia, Singapore |