The word for 'first' is only primeru. For all higer numbers, if the ordinal number is a modifier before a noun, it is suppletive like the Portuguese equivalent, e.g.desimu primeru alunu 'eleventh student' (Portuguese: décimo primeiro aluno).
However, if the ordinal number is not modifying a noun, the cardinal number is used after the preposition di 'of' e.g. ki alunu i di unzi 'that student is the eleventh'.