Twelve has six letters, seventeen has nine.
There is no twelve letter word spelled with the letters 'ntrarxetisan'.
twelve
No, there are no words with more syllables than letters. Syllables are made up of letters, so a word with more syllables would naturally have more letters.
considerably
sixty-twelve
No one word can be made from all of those letters, nor can any word that is more than four letters long.
endsoz
battlefields
mailbox
Venison?
mouse/mice
You are asking us to construct a seven letter word, using twelve letters. This does not seem to be mathematically possible.