Spelling of large numbers

Question

Bonjour,
I am a bit confused about the writing of large numbers, in particular with respect to the use of hyphens and sing./plural for cent.
 
I found the webpage https://about-france.com/french/numbers (cited on the forum) very informative. If I understand it correctly, cent takes an s when round numbers.  With respect to hyphens, it is stated that "Since 1990, the French Academy recommends using hyphens between all the elements of a number that is written in words, unless elements are joined by et". I thus assume no hyphen on both side of the "et" and hyphens elsewhere.
 
Based on the above, I have tried to write the number
471 369 400 881 
in words.
 
Quatre-cent-soixante et onze-milliards-trois-cent-soixante-neuf-millions-quatre-cents-mille-huit-cent-quatre-vingt-un
 
Is this correct? WIth hyphens also between milliards, millions and mille I think it looks a bit messy to read. 
 
Merci et bon week-end!

Céline Pickard · Accepted Answer

Bonjour Terje,
What a big number! This is how the number should be written:
Quatre-cent-soixante-et-onze milliards trois-cent-soixante-neuf millions quatre-cent-mille huit-cent-quatre-vingt-un
In French, "million" and "milliard" are grammatically nouns, not numbers. L'Académie française does recommend attaching hyphens to "million" or "milliard". Also, while "cent" takes an -s in round multiples when it ends a number (quatre cents), it stays singular whenever another numeral follows it (like mille). Finally, under the 1990 rules, hyphens actually connect everything including "et".
https://french.kwiziq.com/revision/grammar/how-to-express-numbers-from-70-to-999
But, this is rather extremely rare that you would be required to write a number such as this one in French. In everyday French and financial contexts, large figures like this are almost always written in digits to avoid this exact clutter.
I hope this is helpful.
Bonne journée !