Home/Chain Registry/Block #6,784,891

Block #6,784,891

2CCLength 11★★★☆☆

Cunningham Chain of the Second Kind · Discovered 4/5/2026, 10:20:39 PM · Difficulty 10.9808 · 7,119 confirmations

2CC

Cunningham Chain of the Second Kind

A sequence where each prime is double the previous prime minus one.

Block Header

Block Hash

62c8bcf6787351037d0a297fd30b5470726f83ad31faf2dc8395a61291fe632a

View on Chainz ↗

Height

#6,784,891

Difficulty

10.980839

Transactions

Size

192 B

Version

536870912

Bits

0afb183f

Nonce

1,546,159,845

Timestamp

4/5/2026, 10:20:39 PM

Confirmations

7,119

Merkle Root

fa460421c77ee8e9ace7cdb77005f4c96f83c1ed04b52b5308c237beb6e8ae90

Transactions (1)

Coinbasefa460421c77ee8…c237beb6e8ae90

1 in → 1 out8.1790 XPM101 B

AMrLYUQN…jwjifxiz

Prime Chain Origin

This is the prime chain origin stored in the block header. It is a composite number (not prime itself) — it equals the first prime in the chain multiplied by a primorial. The origin anchors the entire chain to this specific block.

1.360 × 10⁹⁷(98-digit number)

13607719797873439178…34041888090571991040

Discovered Prime Numbers

p_k = 2^k × origin + 1

These are the actual prime numbers discovered by this block, computed using the verified Primecoin formula. Each number has been independently confirmed to pass the Fermat primality test. Use the FactorDB links to verify any number independently.

origin + 1

1.360 × 10⁹⁷(98-digit number)

13607719797873439178…34041888090571991041

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^1 × origin + 1

2.721 × 10⁹⁷(98-digit number)

27215439595746878356…68083776181143982081

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^2 × origin + 1

5.443 × 10⁹⁷(98-digit number)

54430879191493756712…36167552362287964161

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^3 × origin + 1

1.088 × 10⁹⁸(99-digit number)

10886175838298751342…72335104724575928321

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^4 × origin + 1

2.177 × 10⁹⁸(99-digit number)

21772351676597502684…44670209449151856641

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^5 × origin + 1

4.354 × 10⁹⁸(99-digit number)

43544703353195005369…89340418898303713281

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^6 × origin + 1

8.708 × 10⁹⁸(99-digit number)

87089406706390010739…78680837796607426561

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^7 × origin + 1

1.741 × 10⁹⁹(100-digit number)

17417881341278002147…57361675593214853121

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^8 × origin + 1

3.483 × 10⁹⁹(100-digit number)

34835762682556004295…14723351186429706241

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^9 × origin + 1

6.967 × 10⁹⁹(100-digit number)

69671525365112008591…29446702372859412481

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^10 × origin + 1

1.393 × 10¹⁰⁰(101-digit number)

13934305073022401718…58893404745718824961

Verify on FactorDB ↗Wolfram Alpha ↗

What this block proved

The miner who found this block proved the existence of 11 consecutive prime numbers forming a Cunningham Chain of the Second Kind. The prime chain origin — the large number shown above — anchors the chain and is divisible by a primorial (the product of small primes), cryptographically tying these prime numbers to this specific block.

View full Prime Chain Discovery page →

★★★☆☆

Rarity

RareChain length 11

How Primecoin's Proof-of-Work Constructs These Primes

Primecoin stores a value called the prime chain origin in each block. The miner found a large integer such that when divided by a primorial (the product of small primes: 2 × 3 × 5 × 7 × …), the result is the first prime in the chain. The origin is deliberately divisible by this primorial — that divisibility is part of the proof.

Prime Chain Origin = First Prime × Primorial (2·3·5·7·11·…)

Source: Primecoin prime.cpp — CheckPrimeProofOfWork()

This is why the origin has many small prime factors — those factors are the primorial divisor. The chain then extends from the first prime using the 2CC formula:

2CC: p₁ (first prime), p₂ = 2p₁ − 1, p₃ = 2p₂ − 1, …

Verify on a Primecoin Node

Anyone running a Primecoin node can independently verify this block using the following RPC commands. Run these from the primecoin-cli command line or via the debug console in the Primecoin wallet.

1. Get block hash by height

getblockhash 6784891

Returns the block hash for a given block height. Use this to confirm the hash shown above matches the chain.

2. Get full block data

getblock 62c8bcf6787351037d0a297fd30b5470726f83ad31faf2dc8395a61291fe632a

Returns the full block header including difficulty, prime chain origin, prime chain type, transaction IDs, and all other fields shown on this page.

How to run these commands: To verify this data independently, open a terminal on your own Primecoin node and run primecoin-cli <command>. Alternatively, open the Primecoin-Qt wallet, go to Help → Debug Window → Console, and type the command directly. The node must be fully synced to this block height for the commands to return results.

Cross-reference on Chainz Explorer

Chainz is an independent Primecoin block explorer. Compare this block's data to verify accuracy.

View Block #6,784,891 on Chainz ↗