A practical number first
The central point about six in Egypt and Mesopotamia is that most of its appearances are practical. Six is a convenient number: it divides evenly by two and three, and it fits neatly into larger schemes. Scholars generally hesitate to call these uses symbolic unless a text says so. Where a text does supply a reason, it is noted below. The base-60 counting system, in which six alternates with ten, is part of the background, but the focus here is on measures, fractions and divisions of time.
Egypt: measures and the Eye of Horus
The Egyptian cubit, based on the forearm, existed in two common forms: a royal cubit of seven palms, which is 28 digits, and a shorter cubit of six palms, which is 24 digits. The six-palm cubit is a unit used in building and everyday measurement. Nothing in the surviving records suggests it was chosen for symbolic reasons.
A more famous six is the set of fractions associated with the Eye of Horus, or wedjat eye. In scribal arithmetic, the grain measure called the hekat was divided into the fractions one half, one quarter, one eighth, one sixteenth, one thirty-second and one sixty-fourth. These are six fractions, and the sum is 63/64, which falls just short of a whole by 1/64. Modern scholars proposed that the parts of the wedjat eye hieroglyph stood for these fractions, and the idea has been repeated widely. More recent work has questioned how directly the eye parts and the fractions were matched in antiquity, and it is safest to say that both the fractions and the eye sign are real, while the exact link between them is debated. The sequence is also a pure halving series, so the number six here comes from how many halvings the scribes chose to keep, not from any claim about the number itself.
Egyptian time was reckoned in the civil calendar of twelve months of thirty days, with each month divided into ten-day periods (usually called decades), and the night and the day each divided into twelve hours. The ten-day structure ties into the decan stars, which the Egyptians used to tell the hours at night. Six is not the organising number in any of those schemes.
Egypt: the hieroglyph
The Egyptian sign for six is six strokes. They were arranged in two rows of three. The way hieroglyphic numerals group strokes into compact blocks is a matter of convenience in writing. It tells us about scribal layout, not about meaning.
Mesopotamia: the base-60 background
In Sumerian and Akkadian counting, six is the alternate multiplier in the sequence of units: ten, sixty, 600, 3,600. This is the scaffolding of the sexagesimal system and the reason that ancient Mesopotamian writing treats 60 as a main unit. Sixty, not six, is the number that gets attached to a high god, since Anu is given the number 60 in god lists. For six on its own, there is little evidence of ritual importance, apart from its role as a factor in this counting system.
Mesopotamian time and geometry
Babylonian scholars divided the day, counting day and night together, into twelve double hours, a unit called the beru, and each double hour into 30 smaller units, called UŠ. This gives 12 times 30, which is 360 of the smaller units. Around the equinoxes, day and night are about equal, so each would take roughly six of the double hours. The double hour is thus a way of splitting a day into twelve parts, and six appears as half of that division.
A cuneiform tablet from Susa compares the perimeter of a regular hexagon with the circumference of the circle around it. Because the sides of a regular hexagon equal the circle’s radius, the perimeter is six radii, and the tablet’s approach to the ratio shows interest in practical geometry. The hexagon connects with six in a purely geometric way, and the tablet does not present it as a sacred shape. Later traditions about the hexagon and hexagram are a separate matter, and the Pythagorean number philosophy of the Greeks, which treated the perfect number six as special for mathematical reasons, came centuries later.
Where scholars see symbolism
The clearest case of number symbolism in this area is the Mesopotamian practice of giving gods numbers in rank lists, where 60 is the highest. It shows that scribes could attach numbers to deities, but six itself does not stand out in that scheme. Beyond that, the sources are silent on any special meaning for six. Much of what is written popularly about “the meaning of six” in Egypt or Sumer comes from later numerology and is not attested in the records.
Summary of the evidence
Six is a working number in both cultures: a unit of length, a number of fractions, a factor in counting, half of the day divisions. These are documented. Claims that Egyptians or Sumerians revered six as a symbol of harmony, balance or perfection are not supported by the surviving texts, and are best understood as later ideas read back into earlier material.