XPM Prime Explorer symbol
XPMPrime Explorer

Block #6,784,921

1CCLength 10β˜…β˜…β˜†β˜†β˜†

Cunningham Chain of the First Kind Β· Discovered 4/5/2026, 10:43:15 PM Β· Difficulty 10.9809 Β· 11,056 confirmations

1CC
Cunningham Chain of the First Kind

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

Block Header
Block Hash
c0c14c505bcd0d36797411f71c5401dd5a47433ae036173cb571c5b649cc3850
View on Chainz β†—

Height

#6,784,921

Difficulty

10.980867

Transactions

1

Size

191 B

Version

536870912

Bits

0afb1a21

Nonce

665,827,120

Timestamp

4/5/2026, 10:43:15 PM

Confirmations

11,056

Mined by

⛏️ coinsforall.ioAMrLYUQNEy77yWCvavo6WLcMvQjwjifxizVisit pool β†—

Merkle Root

ca9febc3e17f2636e97a4c68e209d488d304e4866c1a01c7f1f78226444c7e51
Transactions (1)
Coinbaseca9febc3e17f26…f78226444c7e51
1 in β†’ 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) β€” it equals the first prime in the chain multiplied by a primorial. The origin anchors the entire chain to this specific block.

3.999 Γ— 10⁹³(94-digit number)
39996810041904016665…09347810573551261919
Discovered Prime Numbers
p_k = 2^k Γ— origin βˆ’ 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.

1
origin βˆ’ 1
3.999 Γ— 10⁹³(94-digit number)
39996810041904016665…09347810573551261919
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2+1 β†’
2
2^1 Γ— origin βˆ’ 1
7.999 Γ— 10⁹³(94-digit number)
79993620083808033330…18695621147102523839
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2+1 β†’
3
2^2 Γ— origin βˆ’ 1
1.599 Γ— 10⁹⁴(95-digit number)
15998724016761606666…37391242294205047679
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2+1 β†’
4
2^3 Γ— origin βˆ’ 1
3.199 Γ— 10⁹⁴(95-digit number)
31997448033523213332…74782484588410095359
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2+1 β†’
5
2^4 Γ— origin βˆ’ 1
6.399 Γ— 10⁹⁴(95-digit number)
63994896067046426664…49564969176820190719
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2+1 β†’
6
2^5 Γ— origin βˆ’ 1
1.279 Γ— 10⁹⁡(96-digit number)
12798979213409285332…99129938353640381439
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2+1 β†’
7
2^6 Γ— origin βˆ’ 1
2.559 Γ— 10⁹⁡(96-digit number)
25597958426818570665…98259876707280762879
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2+1 β†’
8
2^7 Γ— origin βˆ’ 1
5.119 Γ— 10⁹⁡(96-digit number)
51195916853637141331…96519753414561525759
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2+1 β†’
9
2^8 Γ— origin βˆ’ 1
1.023 Γ— 10⁹⁢(97-digit number)
10239183370727428266…93039506829123051519
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2+1 β†’
10
2^9 Γ— origin βˆ’ 1
2.047 Γ— 10⁹⁢(97-digit number)
20478366741454856532…86079013658246103039
Verify on FactorDB β†—Wolfram Alpha β†—

What this block proved

The miner who found this block proved the existence of 10 consecutive prime numbers forming a Cunningham Chain of the First Kind. The prime chain origin β€” the large number shown above β€” anchors the chain and is divisible by a primorial (the product of small primes), cryptographically tying these prime numbers to this specific block.

β˜…β˜…β˜†β˜†β˜†
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 Γ— 3 Γ— 5 Γ— 7 Γ— …), the result is the first prime in the chain. The origin is deliberately divisible by this primorial β€” that divisibility is part of the proof.

Prime Chain Origin = First Prime Γ— Primorial (2Β·3Β·5Β·7Β·11·…)
Source: Primecoin prime.cpp β€” CheckPrimeProofOfWork()

This is why the origin has many small prime factors β€” those factors are the primorial divisor. The chain then extends from the first prime using the 1CC formula:

1CC: p₁ (first prime), pβ‚‚ = 2p₁ + 1, p₃ = 2pβ‚‚ + 1, …
Cross-reference on Chainz Explorer
Circulating Supply:57,611,909 XPMΒ·at block #6,795,976 Β· updates every 60s
xpmprime.info is a work in progress. If you enjoy using this service you can support this project with a Primecoin donation.
AQZeJoQ81VgeHQBpEYTgvNqV1gnz3L5SvK