Although the Hadza, Africa's only remaining hunter-gatherer tribe, do not have words for numbers beyond three or four, some early civilizations employed quite large numbers in their mythology. Mayan texts place mythological events hundreds of millions of years in the past and in the future. Carl Sagan explains that one day and night of the brahma, in ancient Hindu mythology, lasts 8.64 billion years. It may not be surprising then, that the number system now used worldwide (1,2,3,etc) originated in India. That system was later modified and advanced by Arab mathematicians to incorporate decimals, only arrived in Europe around the twelfth century. But even then, this system was not immediately implemented to replace the Roman numeral system.
But what is the Brahma, and how does one of his nights last longer than the Earth or the Sun?
Here is what www.britannica.com had to teach:

Sanskrit Brahman, in the Upanishads (Indian sacred writings), the supreme existence or absolute, the font of all things. The etymology of the Sanskrit is uncertain. Though a variety of views are expressed in the Upanishads, they concur in the definition of brahma as eternal, conscious, irreducible, infinite, omnipresent, spiritual source of the universe of finiteness and change. Marked differences in interpretation of brahma characterize the various subschools of Vedanta, the orthodox system of Hindu philosophy based on the writings of the Upanishads.

According to the Advaita (Nondualist) school of Vedanta, brahma is categorically different from anything phenomenal, and human perceptions of differentiation are illusively projected on this reality. The Bhedabheda (Dualist–Nondualist) school maintains that brahma is nondifferent from the world, which is its product, but different in that phenomenality imposes certain adventitious conditions (upadhis) on brahma. The Visis t advaita (Nonduality of the Qualified) school maintains that a relation between brahma and the world of soul and matter exists that is comparable to the relation between soul and body and that phenomenality is a glorious manifestation of brahma; the school identifies brahma with a personal god, Brahma, who is both transcendent and immanent. The Dvaita (Dualist) school refuses to accept the identity of brahma and world, maintaining the ontological separateness of the supreme, which it also identifies with a personal god.

In early Hindu mythology, brahma is personified as the creator god Brahma and placed in a triad of divine functions: Brahma the creator, Vishnu the preserver, and Siva the destroyer.