Home/Chain Registry/Block #6,784,895

Block #6,784,895

2CCLength 11★★★☆☆

Cunningham Chain of the Second Kind · Discovered 4/5/2026, 10:24:44 PM · Difficulty 10.9808 · 6,832 confirmations

2CC

Cunningham Chain of the Second Kind

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

Block Header

Block Hash

53557a11965d29ad69a61c5dae4c788fb1cafd617464ac49a61c719c9e73fe98

View on Chainz ↗

Height

#6,784,895

Difficulty

10.980839

Transactions

Size

192 B

Version

536870912

Bits

0afb184a

Nonce

742,765,739

Timestamp

4/5/2026, 10:24:44 PM

Confirmations

6,832

Merkle Root

feec330d1d5a9faed1d45b7794e1fb6f956af4fc70ace717032ec304f9db5029

Transactions (1)

Coinbasefeec330d1d5a9f…2ec304f9db5029

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.

7.837 × 10⁹⁷(98-digit number)

78378325903377108100…62735697488969041920

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

7.837 × 10⁹⁷(98-digit number)

78378325903377108100…62735697488969041921

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^1 × origin + 1

1.567 × 10⁹⁸(99-digit number)

15675665180675421620…25471394977938083841

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^2 × origin + 1

3.135 × 10⁹⁸(99-digit number)

31351330361350843240…50942789955876167681

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^3 × origin + 1

6.270 × 10⁹⁸(99-digit number)

62702660722701686480…01885579911752335361

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^4 × origin + 1

1.254 × 10⁹⁹(100-digit number)

12540532144540337296…03771159823504670721

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^5 × origin + 1

2.508 × 10⁹⁹(100-digit number)

25081064289080674592…07542319647009341441

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^6 × origin + 1

5.016 × 10⁹⁹(100-digit number)

50162128578161349184…15084639294018682881

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^7 × origin + 1

1.003 × 10¹⁰⁰(101-digit number)

10032425715632269836…30169278588037365761

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^8 × origin + 1

2.006 × 10¹⁰⁰(101-digit number)

20064851431264539673…60338557176074731521

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^9 × origin + 1

4.012 × 10¹⁰⁰(101-digit number)

40129702862529079347…20677114352149463041

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^10 × origin + 1

8.025 × 10¹⁰⁰(101-digit number)

80259405725058158695…41354228704298926081

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 6784895

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 53557a11965d29ad69a61c5dae4c788fb1cafd617464ac49a61c719c9e73fe98

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 #6,784,895 on Chainz ↗