3

3 (three) is a number, numeral, and glyph. It is the natural number following 2 and preceding 4. Three is the first odd prime number, and the second smallest prime. It is both the first Fermat prime (2 + 1) and the first Mersenne prime (2 − 1), as well as the first lucky prime. However, it's the second Sophie Germain prime, the second Mersenne prime exponent, the second factorial prime (2! + 1), the second Lucas prime, the second Stern prime. Thr... more

3 (three) is a number, numeral, and glyph. It is the natural number following 2 and preceding 4. Three is the first odd prime number, and the second smallest prime. It is both the first Fermat prime (2 + 1) and the first Mersenne prime (2 − 1), as well as the first lucky prime. However, it's the second Sophie Germain prime, the second Mersenne prime exponent, the second factorial prime (2! + 1), the second Lucas prime, the second Stern prime. Three is the first unique prime due to the properties of its reciprocal. Three is the aliquot sum of one number, the square number 4 and is the base of the 3-aliquot tree. Three is the third Heegner number. Three is the second triangular number and it is the only prime triangular number. Three is the only prime which is one less than a perfect square. Any other number which is n − 1 for some integer n is not prime, since it is (n − 1)(n + 1). This is true for 3 as well, but in its case one of the factors is 1. Three non-collinear points determine... less