Error installing Ionic using npm

I am new to Ionic framework. As a starter I installed cordova using npm as npm install -g cordova which installed 6.2.0 successfully. I got following error when installing ionic as npm install -g ionic.

npm: 3.10.5 node: 6.10.2

I also re-installed node, but that dint help me. When I write ionic in cmd i get following error :

I dont know what is the issue with npm or anything else. Any help would be appreciated!

via parth joshi