Owlet puzzle #73
Released Wednesday, September 16, 2026 UTC
8191
the answer for puzzle #73
The five clues
- A four-digit number one less than a power of two.
- A four-digit Mersenne prime.
- It equals 2^n − 1 for a prime n.
- The Mersenne prime M₁₃.
- The Mersenne prime that generates the fifth even perfect number (33,550,336).
Backstory
8191 = 2¹³ − 1 is the fifth Mersenne prime, established by Pietro Cataldi in 1588 alongside 131071. Cataldi's list of primes stood as the largest known for over a century, until Euler pushed the record to 2³¹ − 1 in 1772.
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