Limits RegistryPUBLIC RECORD
Limits RegistryThe generalized Fermat number 2524190^2097152 + 1, with 13,426,224 digits, was found prime on 12 October 2025 by PrimeGrid's Generalized Fermat Prime Search; it ranks sixth among all known primes and is the largest known prime that is not a Mersenne prime. Its primality proof took about 78 days.
The question, scope, and sources behind this Registry record.
The generalized Fermat number 2524190^2097152 + 1, with 13,426,224 digits, was found prime on 12 October 2025 by PrimeGrid's Generalized Fermat Prime Search; it ranks sixth among all known primes and is the largest known prime that is not a Mersenne prime. Its primality proof took about 78 days.
The largest known prime number not of the form 2^p - 1.
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Current frontiers derived from accepted Claims.
An observed or demonstrated result; no opposing bound is implied.
The frontier is not sacred
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≥ when you have shown that at least this value is achievable.≤ when you have shown that anything above this value is impossible.No vibes. State the value, define the scope, and link the paper, proof, code, or reproduction that lets another person check it. Editors review every challenge before the public record changes.
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The frontier as it changed over time.
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1 accepted Claim, with 1 linked evidence records.
Permanent ID limitsregistry.com/limits/LR-LARGEST-KNOWN-NON-MERSENNE-PRIME
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Limits Registry. LR-LARGEST-KNOWN-NON-MERSENNE-PRIME. Largest known prime that is not a Mersenne prime. 2026.