Why do we have to say a Prayer to Deity Hanuman specifically?

Deity Hanuman is an aspect of the God principle and making a prayer to Hanuman can help from following attributes (aside from others):

1. Omnipotent: Among all Deities, it is only Deity Hanuman who cannot be troubled by distressing energy.

2. Master of ghosts: Hanuman is the master of ghosts. Hence, a person possessed by ghosts is taken to a Hanuman temple or is asked to recite verses in praise of Deity Hanuman.

3. Manifest Divine Energy: The Supreme God principle is in Observer mode. It does not perform any function in the universe. The various Deities are aspects of the attributeless God principle that facilitate specific functions in the universe. To carry out any function, manifest Divine Energy is required. Among all the Deities, Hanuman has the maximum manifest Energy. Hence when a person in distress appeals or makes a prayer to Deity Hanuman, he appears early and the reduction in distress is also fast.