It's the only whole number that when spelled out has all its letters in reverse alphabetical order
... Asker's rating 5 out of 5 ... it's not 
rocket science - you only have to go through 10 numbers to figure it out ... Any 
Idea About The Only Number ( When written In English) Whose Letters Are In 
Correct Alphabetical Order ... What do we call 1900-1999 all together?