Is "novecentonovantanovemilanovecentonovantanove" one word? (That's what Treccani seems to suggest, mentioning for example the number "seicentocinquantaquattromilatrecentoventuno", i.e. 654321).

Or should it be "novecentonovantanovemila novecentonovantanove"?

Or "novecento novantanove mila novecento novantanove" (seriously?)? Or in a still different way?


Is there any agreement at all among linguists regarding rules for writing number words in Italian?

What is the longest single-word number in Italian, agreed upon by linguists/dictionaries? "Quattrocentoquarantaquattromilaquattrocentoquarantaquattro"?

Note that "quattrocentoquarantaquattromilaquattrocentoquarantaquattro" would beat "precipitevolissimevolmente" 58-26 in terms of number of characters.


"Centomila" is one word, it is a cardinal numeral adjective; "un milione" is made of two words: "un", masculine indeterminative article, and "milione", masculine noun.

You say "centomila unità" but "un milione di unità" (not "unmilione unità"). Not quite the same.

Also note that 999999 can also be seen as 11110100001000111111 in the binary system, i.e.

219 + 218 + 217 + 216 + 214 + 29 + 25 + 24 + 23 + 22 + 21 + 20

or, by setting b = 2,

1 · b19 + 1 · b18 + 1 · b17 + 1 · b16 + 0 · b15 + 1 · b14 + 0 · b13 + 0 · b12 + 0 · b11 + 0 · b10 + 1 · b9 + 0 · b8 + 0 · b7 + 0 · b6 + 1 · b5 + 1 · b4 + 1 · b3 + 1 · b2 + 1 · b1 + 1 · b0

but my understanding is that these are mathematical representations, not words as used in linguistics.

As to "tutt'al più", this is a "locuzione" (which is made of at least two words) while "tuttalpiù" is one word (1, 2, 3). Of course these are all linguistic conventions, not laws of nature.

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    in italy, when you sign a checque of 999999 euro, you must write the amount also in letters and you write it as one word.
    – rosco
    Feb 5, 2014 at 14:01
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    @rosco This is a good point: in Italy it might happen that you are required to write numbers in letters (and this is also an answer to Bakuriu's remark). But this is not sufficient to guarantee that 999999 is one word: in fact, apparently, according to Treccani 1000000 does not generate one word but two, "un milione" (and not "unmilione").
    – user193
    Feb 5, 2014 at 14:03
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    @randomatlabuser - when you sign a checque for sure you write a single word (without blanks). it is to avoid fraud from the people will receive the checque itself :)
    – rosco
    Feb 5, 2014 at 16:34
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    @rosco True, I meant that it is not necessarily correct from a linguistic point of view but yes, cheque amounts are supposed to be written without blanks, as one word. Thank you for highlighting that.
    – user193
    Feb 5, 2014 at 16:45
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    @egreg We will agree to disagree then. My understanding is that "tutt'al più" and "per lo meno" are made of three words while "tuttalpiù" and "perlomeno" are single words.
    – user193
    Feb 6, 2014 at 18:33

3 Answers 3


I don't think it is one word, but, to begin with, we should agree on the definition of what a word is. Just to make an example from the opposite side, is tutt'al più one word or three? In my opinion this is one word that's written in a peculiar way.

To come to numerals, think to unmilione that would be so written on a check because of legal matters (well, € 1 000 000 would be quite an amount), but in a novel one would write un milione di euro. Is it one word, now?

I often present Mark Twain's


asking whether it is a word or not. In order to be a word, it should have a meaning: can you assign one? Or is vorpale a word? It appears in an Italian translation of Carrol's Jabberwocky (vorpal in the original). Does the presence in a written text guarantee this cluster of letters the status of word? Is ilprogrammadicuinonmenzionomaiilnome one word? Who knows me clearly understands what computer program I'm referring to, but is that a word or many?

We might argue that 999999 is one word because of how it's written. On the other hand, this might be considered just an acronym like СССР, where the three initial letter represent different values:

Союз Советских Социалистических Республик

which are four distinct words. Note that, mathematically, 999999 is an acronym, because it stands for

9 + 9 · b + 9 · b2 + 9 · b3 + 9 · b4 + 9 · b5 + 9 · b6

where b is ten. Is it a word?

  • I disagree with the end of this answer. Mathematically a number is definitely not an acronym, but a single object. The fact that you can decompose it is irrelevant, also because your last point only holds for b<999999.
    – nico
    Feb 6, 2014 at 7:23
  • @nico I was talking about the representation of the number, not about the number.
    – egreg
    Feb 6, 2014 at 7:43
  • I hope Mark Twain didn't write it that way. It should be "konstantinopolitanische Dudelsackpfeifenmachergesellschaft" Feb 8, 2014 at 23:30
  • @WalterTross Mark Twain's spelling was deliberately slightly wrong. Actually the real spelling was Constantinopolitanischerdudelsackspfeifenmachersgesellschafft, I checked in my Penguin edition of the Connecticut Yankee.
    – egreg
    Feb 8, 2014 at 23:34
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    @WalterTross I started from the lowest exponent because I'm a mathematician. ;-)
    – egreg
    Feb 9, 2014 at 0:17

In italiano


alle volte è una sola parola, alle volte è invece

"novecentonovantanovemila e novecentonovantanove"

ergo tre parole, dipende dal contesto!


P.S.=In tutti e due i casi il numero è "999999"

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    Il tuo secondo esempio, semmai, è composto da tre parole. Ma hai seguito la discussione preesistente sul fatto che non è neppure ovvio che sia sufficiente vedere se ci sono degli spazi per decidere se qualcosa è una parola o no?
    – DaG
    Feb 25, 2014 at 17:12

Every number before 1.000.000 is written as a single word, after that "un milione" si added in front, but as a different word

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    Welcome to Italian.SE! A reference would improve a lot this answer.
    – Denis Nardin
    Jun 5, 2018 at 5:32

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