2

Number
$2$ (two) is:


 * The first (strictly) positive even number.


 * The first prime number.


 * The only even number prime number.


 * The first deficient number.


 * The second factorial after $1$:
 * $2 = 1 \times 2$


 * The $3$rd Fibonacci number:
 * $1, 1, 2, \ldots$


 * The first untouchable number.


 * The first primorial.