can a harmful apk file do harm without being downloaded?

[LJ Sal]

I was wondering if a malicious file can do harm without installing the app and just by it being on your phone period?

 

[Rukbat]

If it's on your phone, you downloaded it. If you're absolutely certain that it never ran or was used by another app (the default installer uses .apk files to install the apps), it couldn't have done anything - data doesn't run itself. Just delete it.