1. (one, один, aon, un, hvmken, א) The unit, multiplicative identity, and automorphic in any positional number system. 1 = G-d. Also, 1 = 0.99999… The Messier object, M1, is a remnant supernova in the constellation Taurus.
  2. (two, два, dhá, deux, hokkolen, ב) The oddest prime. the first Sophie Germain prime. A Pell number and highly composite. The first letter in the Torah is bet.
  3. (three, trois, tuccenen, ג )* A Marsenne Prime and the only prime which is one shy a perfect square. An integer is divisible by three if the sum of its digits is divisible by three. 3 is the base of the ternary system.
  4. (four, quatre, osten, ד ) The smallest composite number. The smallest noncyclic group has four elements, the Klein fou-group, which is also the name of a cool math band. Every natural number divisible by four is the difference of two squares. There are four matriarchs of Judaism, Sarah, Rebeccah, Leah, and Rachel.
  5. (five, cinq, cahkepen, ה) A Fermat Prime. No polynomial equation of degree 5 or greater can be solved using a simple formula. The symmetric group, S5, is not solvable. There are five Platonic solids. The Torah cnsists of 5 books.
  6. (six, six, epaken, ו ) The only number which is both perfect and triangular (which happens to be the result of my first theorem). Shavuot begins on the sixth day of Sivan.
  7. (seven, sept, kolvpaken, ז) A happy number. There are seven frieze groups. A group of seven objects is a heptad.
  8. (eight, huit, cenvpaken, ח) A byte is a grouping of eight bits. A Jewish boy undergoes his brit milah on his eighth day.
  9. (nine, neuf, ostvpaken, ט)The first composite lucky number.The only square prime whose aliquot parts also sum up to a square prime. Nine is an exponential factorial, that is, 9 =321 .
  10. (ten, dix, palen, י ) The base of our standard numeral system. Ten is bi. A bi-prime, that is, because it is the product of two primes. There ten plagues, ten days of repentance, and ten generations between Adam and Noah.
  11. (eleven, onze*) To determine if a number is divisible by 11, take the sum of pairs of digits. For example consider 71104. 7 + 11 + 04 = 22, which is 2*11, so 71104 is also divisible by 11.
  12. (twelve, douze) A superfactorial. Twelve is the answer to the three dimensional Kissing Sphere problem (thus, there are twelve green spheres in my userpic). Twelve is sublime. Jewish girls come of age at 12.
  13. (thirteen, treize) there are thirteen Archimedian solids. A Jewish boy comes of age at 13,
  14. (fourteen, quatorze) Discretely bi (prime).
  15. (fifteen, quinze) The smallest number that can be factored using Shor’s quantum algorithm.
  16. (sixteen, seize) the only number of the form xy=yx with x and y different integers.
  17. 17 is the number of wallpaper groups.
  18. the only number that is twice the sum of its digits
  19. 19 is the maximum number of 4th powers needed to sum to any number.
  20. the number of rooted trees with 6 vertices.
  21. 21 is the smallest number of distinct squares needed to tile a square.
  22. 22 is the number of partitions of 8.
  23. 23 is the smallest number of integer-sided boxes that tile a box so that no two boxes share a common length.
  24. 24 is the largest number divisible by all numbers less than its square root.
  25. 25 is the smallest square that can be written as a sum of 2 squares.
  26. 26 is the only number to be directly between a square and a cube.

Most of this is from wikipedia, though at 17 I got impatient and copy/pasted from here

* I either can no longer count in the given language/s or am being lazy about switching to the Hebrew or Russian keyboards. By the by, the languages are: english, russian, irish, french, creek, and hebrew.

The moral of the story is that I’m old today.