showing pop up ads in my android phone

while internet is connected to my phone ads are coming automatically on screen while using.Also some of apps are automatically installed into my phone. 'oto' it is an android app which shows ads.I can't uninstall this app it is show as inbuilt app.Even if disabled it automatically enables and starts showing ads.even after factory reset it is not removed. While i looked in running app i found whatsapp running but i have not installed whatsapp in my device(micromax) .

Welcome to Android Central! See this guide: http://forums.androidcentral.com/amb...p-removal.html

Are you certain those apps weren't preinstalled? If they install themselves and then can't be uninstalled, then you have some kind of malware on the phone. You'll probably have to do a factory reset if respectable antivirus apps (like Malwarebytes or Lookout) can't fix it.