Michael D. Coogan, The Old Testament: A Literary and Historical Introduction to the Hebrew Scriptures, third edition (OUP, 2014), 108.
Given the importance of the Exodus, it is not surprising that the tendency to embellish what had originally occurred is evident among the accounts we have of this central event. For example, how many people escaped from Egypt? Exodus 12.37-38 tells us that the number of the Israelites was “about six hundred thousand men on foot, beside children. A mixed crowd also went up with them, and livestock, in great numbers, both flocks and herds.” Allowing conservatively, one wife for each man and two children for each couple, that adds up to a group of well over two million people, along with their sheep and goats (“flocks”) and cattle (“herds”). This number is impossibly high, being greater than reasonable estimates of the entire population of ancient Egypt. Furthermore, that many people and animals would have left discernible traces in the landscape of the Sinai peninsula, but no evidence has been found of a substantial population living in that arid region at any time.