What is the only number equal to the sum of subfactorials
of its digits?
Hint: it is below 150000
This fact was discovered by Malachy in 1979.
Better late than never: it is MADACHY, not Malachy.
Joseph Steven Madachy ( 1927 – 2014) was a research chemist, technical editor and renowned recreational mathematician. He was the lead editor of Journal of Recreational Mathyematics for about 30 years.