The "Mr. Number" website reports: 1-646-604-7827 is not a valid number. If you are sure that you got a phone call from a number beginning with this prefix, the caller may have 'spoofed' caller ID.
The 604 prefix is not legitimate for that area code.
Robo call selling ways to gyp the govt out of money for a back-brace. Where is the "Do Not Call" people? I get at least one call from these people each day. If you block their number another pops up tomorrow. 646-604-7827 is a telemarketer. Don't waste your time.