Block #6,784,926

2CCLength 10★★☆☆☆

Cunningham Chain of the Second Kind · Discovered 4/5/2026, 10:49:39 PM · Difficulty 10.9809 · 228 confirmations

2CC

Cunningham Chain of the Second Kind

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

Block Header

Block Hash

5bb7f13351ebeab298a0a3e44628cbb216be64e3f71fbd420bd332cb4da017f8

View on Chainz ↗

Height

#6,784,926

Difficulty

10.980865

Transactions

Size

190 B

Version

536870912

Bits

0afb19f8

Nonce

966,878,754

Timestamp

4/5/2026, 10:49:39 PM

Confirmations

228

Merkle Root

ef5e51ffce5dc00e9e39986f5091942295cd0ad0905f2ebd615c37b0e5a6fb66

Transactions (1)

Coinbaseef5e51ffce5dc0…5c37b0e5a6fb66

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.

7.838 × 10⁹²(93-digit number)

78388752466171045713…43616316553791395601

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

7.838 × 10⁹²(93-digit number)

78388752466171045713…43616316553791395601

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^1 × origin + 1

1.567 × 10⁹³(94-digit number)

15677750493234209142…87232633107582791201

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^2 × origin + 1

3.135 × 10⁹³(94-digit number)

31355500986468418285…74465266215165582401

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^3 × origin + 1

6.271 × 10⁹³(94-digit number)

62711001972936836571…48930532430331164801

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^4 × origin + 1

1.254 × 10⁹⁴(95-digit number)

12542200394587367314…97861064860662329601

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^5 × origin + 1

2.508 × 10⁹⁴(95-digit number)

25084400789174734628…95722129721324659201

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^6 × origin + 1

5.016 × 10⁹⁴(95-digit number)

50168801578349469256…91444259442649318401

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^7 × origin + 1

1.003 × 10⁹⁵(96-digit number)

10033760315669893851…82888518885298636801

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^8 × origin + 1

2.006 × 10⁹⁵(96-digit number)

20067520631339787702…65777037770597273601

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^9 × origin + 1

4.013 × 10⁹⁵(96-digit number)

40135041262679575405…31554075541194547201

Verify on FactorDB ↗Wolfram Alpha ↗

What this block proved

The miner who found this block proved the existence of 10 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

UncommonChain length 10

Roughly 1 in 100 blocks. Solid but expected in a healthy network.

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