I’ve never heard about 153 being the number of nations known in Biblical times. It shoulds “fishy” … I think somebody made that up because it sounded good, and it got spread around without any thoughtful review. How would we know that? How many nations were known to the people of, say, Rome in, say, 944 AD? Or to the people of Spain in 1231? How would we know that??? It’s a guess, at best.
I have also heard it said that in the Bible there were 153 peope who received some special blessing from Jesus. But that sounds fishy to me as well (one event comes to mind in which 5000 people received a blessing from Our Lord, which, as I recall, also involved fish).
153 is a cool number, though… at first glance, you might suspect it to be prime (before you noticed that it was 150 + 3 and thus obviously divisible by 3), but it can actually be sliced and diced a lot of ways.
As you point out, it is the sum of the cube of its digits (1^3 + 5^3 + 3^3). But that only works in a base-10 numbering system, which was not in use in Biblical times, so I doubt that aspect of “153” has any currency in the Gospel message. In other numerical bases it does not work. In hex (base-16), for example, 153 is represented as “99”. In octal (base-8), it would be “231”. In Roman numerals, it would be “CLIII”. Was this aspect of “153” a hidden message for people to discover once base-10 numbering systems became common? That sounds fishy, so I don’t think this aspect of “153” is relevant.
Also, as your web link points out, the square-root of three (which is an irrational number) can be very closely represented by the fraction 265 / 153 (the difference being 0.0000246) - this mathematical fact was well known to ancient Greek dudes (those were some smart guys!)
153 is the product of 17 x 3 X 3, 17 being perfection of the spiritual order and 3 being divine completion.
It is also the summation of 17 (1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17), implying a complete fullness of the significance of 17 (perfection of spiritual order). That’s cool.
It is also the square of 12 (perfection) added to the square of three (divine fulness).
In classical languages, each character had a numerical value associated with it, so it’s sometimes interesting to see what a “word” adds up to (though I think it is often meaningless coincidence, but it’s interesting and possibly significant, since we know that ancient writers sometimes chose words and phrases with specific numeric intent).
The Hebrew expresson “Beni Ha-Elohim” (Sons of God, represented by nine Hebrew characters that I can’t reproduce in this Forum) adds up to 153. Furthermore, the same expression in Greek adds up to 3213, which is 3 x 7 x 153.
The phrase “joint heirs” (“sunkleeronomoi” - Rom 8:17) adds up to 1071, which is 153 x 7 (divine perfection).
The expression “ktisis Theou” (“the creation of God”) adds up to 1224, which is 153 x 8 (super abundance).
The Greek word for “Fishes” is ‘ichthues’ which is also 153 x 8 (super abundance).
There is no question that ancient people realized that 153 was a “special” number (ancient Greeks figured that out). It’s place in the Gospel message is not coincidence.