If the Quran mentioned that the heirs of Kalalah (a person who dies without a direct heir) receive one-sixth of what is left if they are a brother and a sister, then where does the rest of the inheritance go?

What remains of the inheritance after the sharers of the prescribed shares have taken their shares is taken by the 'Asabat (agnate heirs), due to the saying of the Prophet, peace and blessings be upon him: "Give the prescribed shares to those who are entitled to them, and whatever remains is for the closest male." If none of the 'Asabat are present, the remainder is returned to the sharers of the prescribed shares themselves, in proportion to their shares.