\(2^{521}-1=512*2^{512}-1 \approx 6.8647976601306097 imes 10^{156}\) is the largest known Mersenne prime which is also a Woodall number. There are no other such numbers smaller than \(2^{549,755,813,927}-1\). Its full decimal expansion is 6864797660130609714981900799081393217269435300143305409394463459185543183397656052122559640661454554977296311391480858037121987999716643812574028291115057151.