Block #6,784,930

2CCLength 11★★★☆☆

Cunningham Chain of the Second Kind · Discovered 4/5/2026, 10:55:12 PM · Difficulty 10.9809 · 224 confirmations

2CC

Cunningham Chain of the Second Kind

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

Block Header

Block Hash

7c1be912cb43464a21033fdd8f7cacb834abab91914c45d1b8da2f37ae1fd836

View on Chainz ↗

Height

#6,784,930

Difficulty

10.980855

Transactions

Size

191 B

Version

536870912

Bits

0afb194e

Nonce

1,636,484,910

Timestamp

4/5/2026, 10:55:12 PM

Confirmations

224

Merkle Root

714b98b804a891fc45715bed1357547321feac2c1a01800be3293c509e7a52b3

Transactions (1)

Coinbase714b98b804a891…293c509e7a52b3

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.

1.236 × 10⁹⁴(95-digit number)

12360153474512968282…80107312298251842901

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

1.236 × 10⁹⁴(95-digit number)

12360153474512968282…80107312298251842901

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^1 × origin + 1

2.472 × 10⁹⁴(95-digit number)

24720306949025936564…60214624596503685801

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^2 × origin + 1

4.944 × 10⁹⁴(95-digit number)

49440613898051873129…20429249193007371601

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^3 × origin + 1

9.888 × 10⁹⁴(95-digit number)

98881227796103746259…40858498386014743201

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^4 × origin + 1

1.977 × 10⁹⁵(96-digit number)

19776245559220749251…81716996772029486401

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^5 × origin + 1

3.955 × 10⁹⁵(96-digit number)

39552491118441498503…63433993544058972801

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^6 × origin + 1

7.910 × 10⁹⁵(96-digit number)

79104982236882997007…26867987088117945601

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^7 × origin + 1

1.582 × 10⁹⁶(97-digit number)

15820996447376599401…53735974176235891201

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^8 × origin + 1

3.164 × 10⁹⁶(97-digit number)

31641992894753198803…07471948352471782401

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^9 × origin + 1

6.328 × 10⁹⁶(97-digit number)

63283985789506397606…14943896704943564801

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^10 × origin + 1

1.265 × 10⁹⁷(98-digit number)

12656797157901279521…29887793409887129601

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.

★★★☆☆

Rarity

RareChain length 11

Approximately 1 in 1,000 blocks. Noteworthy discoveries.

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, …

Cross-reference on Chainz Explorer