2,305,843,009,213,693,951/Historical Note

Historical Note on $2 \, 305 \, 843 \, 009 \, 213 \, 693 \, 951$
$2 \, 305 \, 843 \, 009 \, 213 \, 693 \, 951 = 2^{61} - 1$ was discovered to be prime in $1883$ by.

It was discovered independently in $1886$ by, and confirmed by in $1887$.

It was the $10$th Mersenne prime to be discovered, although the $9$th in sequence.

had demonstrated in $1876$ that $2^{127} - 1$ (actually the $12$th in sequence) is prime.