1. The SSA database uses COBOL, which does not have a date type, but rather codes dates to a reference point, most commonly May 20, 1875. If birthdate information is incomplete, you end up with erroneous age information.
2. This screenshot lists ~400 million people marked as alive in the SSA database. That is more people than are currently alive in the United States, and almost five times more than are currently receiving SS benefits.
3. Only about 2% of people marked as older than 100 years old in the database are currently receiving benefits, and the SSA has automatically stopped paying out benefits to anyone marked as older than 115 in the database since 2015.