Block #6,784,939

2CCLength 10★★☆☆☆

Cunningham Chain of the Second Kind · Discovered 4/5/2026, 11:04:28 PM · Difficulty 10.9809 · 215 confirmations

2CC

Cunningham Chain of the Second Kind

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

Block Header

Block Hash

f43ca6cb72bdd8741c60a51bc9c5fc9f01c4c3af710d2bee21e9e227a5393c25

View on Chainz ↗

Height

#6,784,939

Difficulty

10.980858

Transactions

Size

191 B

Version

536870912

Bits

0afb197c

Nonce

515,824,422

Timestamp

4/5/2026, 11:04:28 PM

Confirmations

215

Merkle Root

34f207831f92f12cee2ffd5fb6d04dc63cd893cfa69792a0b73d5e440eaa10cd

Transactions (1)

Coinbase34f207831f92f1…3d5e440eaa10cd

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.

2.595 × 10⁹⁴(95-digit number)

25959972029425347968…25239185426770828481

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

2.595 × 10⁹⁴(95-digit number)

25959972029425347968…25239185426770828481

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^1 × origin + 1

5.191 × 10⁹⁴(95-digit number)

51919944058850695936…50478370853541656961

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^2 × origin + 1

1.038 × 10⁹⁵(96-digit number)

10383988811770139187…00956741707083313921

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^3 × origin + 1

2.076 × 10⁹⁵(96-digit number)

20767977623540278374…01913483414166627841

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^4 × origin + 1

4.153 × 10⁹⁵(96-digit number)

41535955247080556749…03826966828333255681

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^5 × origin + 1

8.307 × 10⁹⁵(96-digit number)

83071910494161113498…07653933656666511361

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^6 × origin + 1

1.661 × 10⁹⁶(97-digit number)

16614382098832222699…15307867313333022721

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^7 × origin + 1

3.322 × 10⁹⁶(97-digit number)

33228764197664445399…30615734626666045441

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^8 × origin + 1

6.645 × 10⁹⁶(97-digit number)

66457528395328890798…61231469253332090881

Verify on FactorDB ↗Wolfram Alpha ↗

×2−1 →

2^9 × origin + 1

1.329 × 10⁹⁷(98-digit number)

13291505679065778159…22462938506664181761

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