A interesting list at
http://www.stetson.edu/~efriedma/numbers.html , listed the special meaning of number between 0 to 9999.
0 is the
additive identity.
1 is the
multiplicative identity.
2 is the only even
prime.
3 is the number of spatial dimensions we live in.
4 is the smallest number of colors sufficient to color all planar maps.
5 is the number of
Platonic solids.
6 is the smallest
perfect number.
7 is the smallest number of faces of a regular polygon that is not
constructible by straightedge and compass.
8 is the largest
cube in the
Fibonacci sequence.
9 is the maximum number of
cubes that are needed to sum to any positive integer.
10 is the base of our number system.
11 is the largest known
multiplicative persistence.
12 is the smallest
abundant number.
13 is the number of
Archimedian solids.
14 is the smallest number n with the property that there are no numbers
relatively prime to n smaller numbers.
15 is the smallest
composite number n with the property that there is only one
group of order n.
16 is the only number of the form xy = yx with x and y different integers.
17 is the number of
wallpaper groups.
18 is the only number that is twice the sum of its digits.
19 is the maximum number of 4th powers needed to sum to any number.
20 is the number of
rooted trees with 6 vertices.
21 is the smallest number of distinct
squares needed to tile a
square.
22 is the number of
partitions of 8.
23 is the smallest number of integer-sided boxes that tile a box so that no two boxes share a common length.
24 is the largest number divisible by all numbers less than its
square root.
25 is the smallest
square that can be written as a sum of 2
squares.
26 is the only positive number to be directly between a
square and a
cube.
27 is the largest number that is the sum of the digits of its
cube.
28 is the 2nd
perfect number.
29 is the 7th
Lucas number.
30 is the largest number with the property that all smaller numbers
relatively prime to it are
prime.
31 is a
Mersenne prime.
32 is the smallest 5th power (besides 1).
33 is the largest number that is not a sum of distinct
triangular numbers.
34 is the smallest number with the property that it and its neighbors have the same number of
divisors.
35 is the number of
hexominoes.
36 is the smallest number (besides 1) which is both
square and
triangular.
37 is the maximum number of 5th powers needed to sum to any number.
38 is the last
Roman numeral when written lexicographically.
39 is the smallest number which has 3 different
partitions into 3 parts with the same product.
40 is the only number whose letters are in alphabetical order.
41 is the smallest odd number that is not of the form | 2x - 3y |.
42 is the 5th
Catalan number.
43 is the number of sided
7-iamonds.
44 is the number of
derangements of 5 items.
45 is a
Kaprekar number.
46 is the number of different arrangements (up to rotation and reflection) of 9 non-attacking
queens on a 9×9 chessboard.
47 is the largest number of
cubes that cannot tile a
cube.
48 is the smallest number with 10
divisors.
49 is the smallest number with the property that it and its neighbors are
squareful.
50 is the smallest number that can be written as the sum of of 2
squares in 2 ways.
51 is the 6th
Motzkin number.
52 is the 5th
Bell number.
53 is the only two digit number that is reversed in
hexadecimal.
54 is the smallest number that can be written as the sum of 3
squares in 3 ways.
55 is the largest
triangular number in the
Fibonacci sequence.
56 is the number of reduced 5×5
Latin squares.
57 = 111 in base 7.
58 is the number of
commutative semigroups of order 4.
59 is the number of
stellations of an icosahedron.
60 is the smallest number divisible by 1 through 6.
61 is the 6th
Euler number.
62 is the smallest number that can be written as the sum of of 3 distinct
squares in 2 ways.
63 is the number of
partially ordered sets of 5 elements.
64 is the smallest number with 7
divisors.
65 is the smallest number that becomes
square if its reverse is either added to or subtracted from it.
66 is the number of
8-iamonds.
67 is the smallest number which is
palindromic in bases 5 and 6.
68 is the 2-digit string that appears latest in the decimal expansion of
π.
69 has the property that n2 and n3 together contain each digit once.
70 is the smallest
abundant number that is not the sum of some subset of its
divisors.
71 divides the sum of the
primes less than it.
72 is the maximum number of
spheres that can touch another
sphere in a lattice packing in 6 dimensions.
73 is the smallest number (besides 1) which is one less than twice its reverse.
74 is the number of different non-
Hamiltonian polyhedra with minimum number of vertices.
75 is the number of orderings of 4 objects with ties allowed.
76 is an
automorphic number.
77 is the largest number that cannot be written as a sum of distinct numbers whose reciprocals sum to 1.
78 is the smallest number that can be written as the sum of of 4 distinct
squares in 3 ways.
79 is a permutable
prime.
80 is the smallest number n where n and n+1 are both products of 4 or more
primes.
81 is the
square of the sum of its digits.
82 is the number of
6-hexes.
83 is the number of
zero-less pandigital squares.
84 is the largest order of a
permutation of 14 elements.
85 is the largest n for which 12+22+32+...+n2 = 1+2+3+...+m has a solution.
86 = 222 in base 6.
87 is the sum of the
squares of the first 4
primes.
88 is the only number known whose
square has no isolated digits.
89 = 81 + 92
90 is the number of degrees in a right angle.
91 is the smallest
pseudoprime in base 3.
92 is the number of different arrangements of 8 non-attacking
queens on an 8×8 chessboard.
93 = 333 in base 5.
94 is a
Smith number.
95 is the number of
planar partitions of 10.
96 is the smallest number that can be written as the difference of 2
squares in 4 ways.
97 is the smallest number with the property that its first 3 multiples contain the digit 9.
98 is the smallest number with the property that its first 5 multiples contain the digit 9.
99 is a
Kaprekar number.
100 is the smallest
square which is also the sum of 4 consecutive
cubes.
The full list is heret