The number 31

Offspring, progeny, family

Scripture's clearest occurrence of thirty-one is a list: Joshua's conquest defeated thirty-one kings west of the Jordan, tallied by name and closing 'all the kings thirty and one' (Joshua 12:9-24). Bullinger's Number in Scripture assigns the number a different meaning from this site's label: he ties it to the Hebrew word for God, El, whose letters total thirty-one in gematria, and calls its signification 'Deity.' That is not the same tradition as 'offspring, progeny, family' (Ed F. Vallowe, Biblical Mathematics, 1998), which has no scriptural anchor describing offspring. The two traditions disagree and should be presented as different readings, not conflated; neither is a statement the biblical text makes about itself.

The mathematics

31 = 2⁵ − 1, a Mersenne prime, written 11111 in binary — the sum of the first five powers of two.
The eleventh prime, and a twin prime with 29.
Thirty-one is mathematics' own warning against forcing a pattern. Put points around a circle and join every pair: two points cut the disc into 2 regions, three into 4, four into 8, five into 16 — and six into 31, not the 32 everyone expects. The sequence runs 1, 2, 4, 8, 16, 31, 57. A pattern that holds five times can still be wrong.

Every property here was checked before it was printed.

What they have said about this number

Deity — thirty-one being the letter-value of El, the name of God.

“The Hebrew expression of this is El, the name of God, and its signification as a number or factor would be Deity.”

E. W. Bullinger, Number in Scripture (1894)

In Hebrew and Greek

Hebrew

Shloshim v'echad (שְׁלוֹשִׁים וְאֶחָד) - thirty-one

Greek

Triakonta kai heis (τριάκοντα καὶ εἷς) - thirty-one

First occurrence

Genesis 1:1

In the beginning God created the heaven and the earth.

The pattern in Scripture

31 kings defeated (Josh 12:24)
Proverbs 31 - virtuous woman
31 chapters in Proverbs

31:31 verses

Genesis 31:31

And Jacob answered and said to Laban, Because I was afraid: for I said, Peradventure thou wouldest t...

Numbers 31:31

And Moses and Eleazar the priest did as the Lord commanded Moses.

Job 31:31

If the men of my tabernacle said not, Oh that we had of his flesh! we cannot be satisfied.

Proverbs 31:31

Give her of the fruit of her hands; and let her own works praise her in the gates.

Jeremiah 31:31

Behold, the days come, saith the Lord, that I will make a new covenant with the house of Israel, and...