Strange 15-digit number for Facebook account on Android


Limp Gawd
Jun 26, 2020
A bit off-topic, but I don't know where to ask. What you see below is a part of someone's Android 11 phone Accounts page (Settings>Accounts). It lists most accounts as usual (App name or email address or phone number), but Facebook account is listed 2 times. One entry is just plain "Facebook" , but the other Facebook entry is a 15 digit number (blurred/smudged on screenshot) that does not correspond to account holder's number or any other known number. Removing that 15-digit account works only until phone accounts are synchronized. Once synchronization takes place, the 15-digit Facebook account entry re-appears.


Does anyone else get that? Is it a token of some kind? Is there any way to verify that? The account holder uses 2-Step App-based authentication and does not provide Facebook the phone's number.