We are not told how many "friends" (see Ether 1:41) left the great tower with Jared and his brother, but after arriving in the New World, Moroni writes that, "the friends of Jared and his brother were in number about twenty and two souls" (Ether 6:16). These twenty two "friends" of Jared and his brother had already "begat sons and daughters before they came to the promised land; and therefore they began to be many."
According to Verneil Simmons, since only males beget, we know that the 22 friends represent heads of households, in the patriarchal sense. Women had no civil status in the social structure of the times and would not have been included in the census, nor included in the genealogy lists. They were considered as property of their husbands. [Verneil W. Simmons, Peoples, Places and Prophecies, p. 27]
According to Glenn Scott, the number "twenty and two" must mean the number of families that had made the sea voyage together. If the average number of children per family was somewhere between those of Jared and his brother (see Ether 6:20), the total would have been about 456 persons (17 children + 2 parents x 24 families averaging nineteen person each, totaling about 57 per vessel plus animals and fowls, which was probably about the practical maximum for such an extended voyage. [Glenn A. Scott, Voices from the Dust: New Light on an Ancient American Record, pp. 41, 44]