is my phone najis

i take my phone to the bathroom and place it on the counter and sometimes i touch it when i’m in the bathroom but i can’t remember if i touched it with najis hands or not but i do not see any sort of sign of impurity on my phone, i sometimes pray with this phone in my pocket or with this phone in front of me if i forget the last part of prayer and my head touches it is my phone najis and my prayers invalid