'Sixty six' in the Bible

All the persons belonging to Jacob, who came to Egypt, his direct descendants, not including the wives of Jacob’s sons, were sixty-six persons in all,

But if she bears a female child, then she shall be unclean for two weeks, as in her menstruation; and she shall remain in the blood of her purification for sixty-six days.

Here is wisdom. Let him who has understanding calculate the number of the beast, for the number is that of a man; and his number is six hundred and sixty-six.