general_fact: 53172 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 53172 is an unremarkable number.
trivia: 53172 is a boring number.
historical_date: July 30th is the day in 1965 that U.S. President Lyndon B. Johnson signs the Social Security Act of 1965 into law, establishing Medicare and Medicaid.