281

Number
$281$ (two hundred and eighty-one) is:


 * The $60$th prime number


 * The $1$st of a triplet of consecutive integers which have the property that if their digits are multiplied, and the process repeated on the result until only $1$ digit remains, that final digit is the same for all three:
 * $2 \times 8 \times 1 = 16$; $1 \times 6 = 6$


 * The smaller of the $19$th pair of twin primes, with $283$


 * The $19$th Sophie Germain prime after $2$, $3$, $5$, $11$, $23$, $29$, $41$, $53$, $83$, $89$, $113$, $131$, $173$, $179$, $191$, $233$, $239$, $251$:
 * $2 \times 281 + 1 = 563$, which is prime.


 * The $26$th minimal prime base $10$ after $11$, $13$, $17$, $19$, $23$, $29$, $31$, $37$, $41$, $43$, $47$, $53$, $59$, $61$, $67$, $71$, $73$, $79$, $83$, $89$, $97$, $227$, $251$, $257$, $277$