Cognomen Еркки (Еркки 
, Itkonen 
) , around the world, is quite a rare family name. The cognomen Еркки is habitual in Northern Europe, particularly Finland, where it is quite a common surname, Estonia, where it is quite a rare surname, and Sweden, where it is a rare surname. Measured by absolute frequency, it most frequently occurs in Finland, Sweden, and the United States.