After dešimt (ten), of course, go the following numbers:

11 vienuolika
12 dvylika
13 trylika
14 keturiolika
15 penkiolika
16 šešiolika
17 septyniolika
18 aštuoniolika
19 devyniolika

They behave the same way as dešimt: they require the plural genitive case:

vienuolika futbolininkų (11 footballers)
dvylika futbolininkių (12 female footballers)

However they have cases:

Their endings are just like those of feminine nouns (-a), except for the accusative case: the accusative case exactly like the nominative - without the nasal ą.

Mums reikia penkiolikos žaidėjų. We needs fifteen players.
Mes jau buvome devyniolikoje šalių. We have already been in nineteen countries.