What is the only integer whose spelling in English arranges its letters alphabetically?

Forty

Which Christmas hymn's Latin title is 'Adeste Fideles'? What was the name of Captain Nemo's submarine in "20,000 Leagues Under the Sea"? In the Czech Republic, young women toss a shoe over their shoulders during Christmas to predict what? Which group of laws enforced racial segregation and discrimination in the southern U.S. after Reconstruction? Who created the notation 'f(x)' for a function?