In the Sumerian King List, kings are listed to have reigned for tens of thousands of years. For example

In Larag, En-sipad-zid-ana ruled for 28800 years

Yet, in the same record we see

In Hamazi, Hadanic became king; he ruled for 360 years

and

Apil-kin ruled for 3 years

My immediate (and obviously ill-informed) inclination was that these ages were symbolic, meant to represent a long and prosperous reign as compared to a short and ineffective one. However, seeing such specific lengths such as

Aga, the son of En-men-barage-si, ruled for 625 years. (ms. P3+BT14 adds:) 1525 are the years of the dynasty of En-men-barage-si. 23 kings; they ruled for 24510 years, 3 months, and 3 1/2 days.

seems to contradict my own best guess. If the point was to communicate a long rule, why not just state a large number instead of creating a very specific amount of time, down to the half-day?

What is the significance of these recordings? Is there a discrepancy in how we interpret lengths of time in our modern society or are these numbers symbolic/religious in some way?