digit - would be nice, if it would always, in all contexts, mean "a sign used for writing numbers"; unfortunately, it frequently means a finger.
number - as in "twenty-six phonetic symbols, ten numbers, and about eight punctuation marks" - but it can't be a translation for "cifra", because "cifra" is not a number, it's a graphical character. Calling it a number is calling for confusion.
figure - as in "six-figure salary" - won't work, because it's only sixth meaning of the word. Even the numbers on the clock are called figures (and 10, 11 and 12 aren't - they are two-figure numbers); body shape is called a figure, a figure of speech and figurehead all come before the usage of figure as a digit.
cipher - would be a false friend, same root, same word, but it doesn't mean "a graphic digit" (and don't take "graphic" to mean "obscene" and "digit" to mean "finger"), it's an encryption. And it even means "number zero".