41

Number
$41$ (forty-one) is:


 * The $13$th prime number, after $2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37$


 * The $5$th of the sequence of $n$ such that $p_n \# - 1$, where $p_n \#$ denotes primorial of $n$, is prime:
 * $3, 5, 11, 13, 41$


 * The smallest prime number which is not the difference between a power of $2$ and a power of $3$.

Also see

 * Smallest Prime Number not Difference between Power of 2 and Power of 3