Yes, it's legit.  I searched the Prudential web site and didn't find the number, so called 800-778-2255, to verify the letter and number.  Cust Svc Rep (CSR) was very nice and verified the letter and number, then w/o having to hang-up and call the number on the letter, took care of me right away.

Saying my mother, who has been dead for 4 years is the insured on a Prudential insurance police and may be deceased but no claim for death benefits has been submitted.  Is this number safe to call?  This was a letter leaving this number to call.