In a 1998 issue of Vetus Testamentum, the scholars journal on the Old Testament, British scientist Colin Humphreys, author of book The Miracles of Exodus, came up with a reasonable re-interpretation of the above quoted passage.
For Humphreys, it all boiled down to a key word, eleph, translated as a thousand in the Numbers passage. But eleph also carries the meaning of a group, such as a family, clan, or troop.
Numbers 1:21 states that the number of fighting men in the tribe of Reuben was 46,500. In the Hebrew text, this is represented as 46 eleph and 500 men, traditionally rendered as 46 thousand and 500 men. Humphreys suggests it should be read as: 46 troops and 500 men. That is, the tribe of Reuben contributed 500 men (46 troops), not 46,500.
A troop would have between 10 and 20 men, which was standard for armies at the time (supported by data contained in the 14th-century BCE Amarna tablets of Egypt).
All in all, Humphreys, employing a sophisticated mathematical analysis, calculated a total of 5,550 men making up Moses fighting force. And a more realistic estimate of the number of Israelites participating in the Exodus would be about 20 thousand, not the multitude recorded in Scripture, but enough to have guaranteed the birth of a nation.
(For the reader interested in the complete Humphreys reference mentioned above, see the NOTE appended to the blog.)
The idea of 2-million Israelites wandering around in the desert for forty years is unrealistic. The number is unwieldy, as already indicated, and there wouldn’t have been enough water available for their needs. But 20-thousand Israelites could have survived in the Sinai Peninsula. Modern biblical critics dismiss the saga of the Exodus as nothing more than theology told in the form of history, but we now have some credible support from the scientific community for the story’s authenticity.
NOTE: Colin J. Humphreys, The Number of People in the Exodus from Egypt: Decoding Mathematically the Very Large Number in Numbers I and XXVI. Vetus Testamentum 48 (1998), pp. 196-213.