Telegram is good and bad in the same time, because don't forget that he is full of scammers too, I mean if you made one mistake you can be victim, but in my opinion I think this app is good to follow some channels to earn from them not to give them.
Thare many applications to protect your mobile from viruses, the most important of which are Kaspersky, lookout mobile security, Norton and Security 360. For me, I prefer Kaspersky, but it is somewhat heavy on the mobile.