There are three mysterious triangular numbers in the New Testament. The first is 153 which occurs in John 21:11. The second is 276 which occurs in Acts 27:37. And the third is 666 which occurs in Revelations 13:18.
These three numbers have certain curious relationships with each other, which I will endeavor to illuminate.
First, there are some elementary properties we should notice. Using the formula for the nth triangular number, T(n)=n(n+1)/2, it's easy to see that 153 is the 17th triangular number, 276 is the 23rd triangular number, and 666 is the 36th triangular number. And 36 is the square of 6.
Also, we note that the greatest common divisor of these three triangular numbers is 3. Notice also that 3 is the divine number, since it represents the Godhead.
The three largest prime numbers that divide each of the three without dividing the other two are 17, 23, and 37, for 153 is divisible only by 17, and 276 is divisible only by 23, and 666 is divisible only by 37.
Looking at the context of the verses cited above, we notice that the three triangular number have some sort of connection with water, which is one of the primordial elements mentioned in 2 Peter 3:5. The number 666 is of course the infamous "number of the Beast", and in Revelations 13:1 the Beast is said to come up out of the sea. As for the other two numbers' connection with water, that is left as an excercise for the reader.
The sum of the three triangular number is 1095, which when divided by 3 gives 365, the number of days in a year, the primary unit for measuring the seasons.
The three prime divisors 17, 23, and 37 that were mentioned are when added together the sum 77. The number 7 occuring very frequently in the Scriptures as the number of completion.
Using 7 as a modulus, and 3 as the base, the discrete logarithms of the three triangular numbers are respectively 9, 7, and 6. This is because under modular congruencies 3^9=153 and 3^7=276 and 3^6=666 under modulo 7. Furthermore, the product of 9×7×6 is the number 378. But the number 378 is itself the 27th triangular number, 27 being the cube of 3.
We can make the observation that (17+23+37)+(9+7+6)=99. However, the number 9 is the number peculiar to the angelic creation (whereas 6 is peculiar to Man). And 9 happens to be the square of 3.
That 2²+3²+5²+7²+11²+13²+17²=666 is also very curious. In other words, the "number of the Beast" is also the sum of the squares of the prime numbers up through 17, which was the prime divisor we associated with 153.
It was on the 17th day in the month that the Noachian Flood struck (Genesis 7:11). And it was also on the 17th day that Noah's Ark came to rest in the mountains of Ararat (Genesis 8:4). This is the first occurrence of the number 17 in the Scriptures. And here also is another connection with water. The last occurrence of 17 happens to be in Jeremiah 32:9, where Jeremiah the prophet redeems his inheritance in Anathoth for 17 shekels of silver.
The prime divisor 23 associated with 276 also has an odd connection with humanity. Supposedly there are 23 chromosome pairs in human cells. And there are 23 disks in the human spine.
The number pair 23 and 7, which are associated with 276, happen to occur together in 2 Chronicles 7:10, where it is recorded that the 23rd day of the 7th month marked the joyful ending of the dedication of the first Temple, which was built by Solomon.
As for 37, which is associated with 666, there are supposed to be 37 genes in the human mitochondrial genome. And it requires 37 skeletal muscles to move the human hand.
[I'll see what other things turn up about these numbers and add to this later]