As far as I am aware, no, it is not. So far there is only one phone that I know of that is currently Alexa compatible and that it the HTC U11 phone. Others will probably come along later.
From a recent Amazon Alexa email:
Alexa in your pocket
The HTC U11 is the first smartphone with hands-free access to Alexa. No need to open an app or press a button—control smart home devices, check the weather, and more when you're on the go.