Coconut milk factor is : -

Coconut milk (the liquid endosperm of coconut) stimulates cell division in plant tissue cultures. This activity was called the coconut milk factor.
The active substance is a cytokinin; the natural cytokinin zeatin was first isolated from corn kernels, and coconut milk contains zeatin and related cytokinins.
Cytokinins promote cell division (cytokinesis), and coconut milk is added to culture media for this reason.
So the coconut milk factor is a cytokinin.