O programa 'npm' não está atualmente instalado, apesar de instalado

Question

prashanth@DELL-PK:~$ sudo apt-get install nodejs
Reading package lists... Done
Building dependency tree       
Reading state information... Done
nodejs is already the newest version (4.2.6~dfsg-1ubuntu4.1).
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

prashanth@DELL-PK:~$ npm install
The program 'npm' is currently not installed. You can install it by typing:
sudo apt install npm