Owlet puzzle #49
Released Sunday, August 23, 2026 UTC
121
the answer for puzzle #49
The five clues
- A three-digit palindrome divisible by 11.
- A three-digit palindromic square.
- A palindromic square whose root is a two-digit palindromic prime.
- Equal to 11², and also 5! + 1.
- One of only three known solutions to Brocard's problem n!+1 = m² (n=4,5,7 giving 25, 121, 5041).
Backstory
121 = 11² and equals 5! + 1: the second known solution to Brocard's problem n! + 1 = m². The three known solutions are (n,m) = (4,5), (5,11), and (7,71); no fourth is known below n = 10¹². Also 121 is a palindromic square whose root 11 is itself a palindromic prime.
▶ Play puzzle #49 in practice mode
Or try today's fresh puzzle · Browse the full archive