Block #6,784,937

2CCLength 11★★★☆☆

Cunningham Chain of the Second Kind · Discovered 4/5/2026, 11:00:57 PM · Difficulty 10.9809 · 217 confirmations

2CC

Cunningham Chain of the Second Kind

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

Block Header

Block Hash

c63adcd36b8a927432eb33884d8fc631c46b1afa6b167b00f8b41b00098f9b64

View on Chainz ↗

Height

#6,784,937

Difficulty

10.980860

Transactions

Size

192 B

Version

536870912

Bits

0afb199f

Nonce

132,196,197

Timestamp

4/5/2026, 11:00:57 PM

Confirmations

217

Merkle Root

ba9e5000de1dea7368064abffa51f04340417acd698e67b5672056887f40b618

Transactions (1)

Coinbaseba9e5000de1dea…2056887f40b618

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.

8.530 × 10⁹⁶(97-digit number)

85308765077609853266…15298103959498672641

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

8.530 × 10⁹⁶(97-digit number)

85308765077609853266…15298103959498672641

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^1 × origin + 1

1.706 × 10⁹⁷(98-digit number)

17061753015521970653…30596207918997345281

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^2 × origin + 1

3.412 × 10⁹⁷(98-digit number)

34123506031043941306…61192415837994690561

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^3 × origin + 1

6.824 × 10⁹⁷(98-digit number)

68247012062087882613…22384831675989381121

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^4 × origin + 1

1.364 × 10⁹⁸(99-digit number)

13649402412417576522…44769663351978762241

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^5 × origin + 1

2.729 × 10⁹⁸(99-digit number)

27298804824835153045…89539326703957524481

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^6 × origin + 1

5.459 × 10⁹⁸(99-digit number)

54597609649670306090…79078653407915048961

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^7 × origin + 1

1.091 × 10⁹⁹(100-digit number)

10919521929934061218…58157306815830097921

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^8 × origin + 1

2.183 × 10⁹⁹(100-digit number)

21839043859868122436…16314613631660195841

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^9 × origin + 1

4.367 × 10⁹⁹(100-digit number)

43678087719736244872…32629227263320391681

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^10 × origin + 1

8.735 × 10⁹⁹(100-digit number)

87356175439472489744…65258454526640783361

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