Block #2,643,360

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.

1.721 × 10⁹⁴(95-digit number)

17218319145749808842…35317799502009203569

Discovered Prime Numbers

Lower: 2^k × origin − 1 | Upper: 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.

Level 0 — Twin Prime Pair (origin ± 1)

origin − 1

1.721 × 10⁹⁴(95-digit number)

17218319145749808842…35317799502009203569

Verify on FactorDB ↗Wolfram Alpha ↗

origin + 1

1.721 × 10⁹⁴(95-digit number)

17218319145749808842…35317799502009203571

Verify on FactorDB ↗Wolfram Alpha ↗

Difference: origin + 1 − origin − 1 = 2 (twin primes ✓)

Level 1 — Twin Prime Pair (2^1 × origin ± 1)

2^1 × origin − 1

3.443 × 10⁹⁴(95-digit number)

34436638291499617685…70635599004018407139

Verify on FactorDB ↗Wolfram Alpha ↗

2^1 × origin + 1

3.443 × 10⁹⁴(95-digit number)

34436638291499617685…70635599004018407141

Verify on FactorDB ↗Wolfram Alpha ↗

Difference: 2^1 × origin + 1 − 2^1 × origin − 1 = 2 (twin primes ✓)

Level 2 — Twin Prime Pair (2^2 × origin ± 1)

2^2 × origin − 1

6.887 × 10⁹⁴(95-digit number)

68873276582999235371…41271198008036814279

Verify on FactorDB ↗Wolfram Alpha ↗

2^2 × origin + 1

6.887 × 10⁹⁴(95-digit number)

68873276582999235371…41271198008036814281

Verify on FactorDB ↗Wolfram Alpha ↗

Difference: 2^2 × origin + 1 − 2^2 × origin − 1 = 2 (twin primes ✓)

Level 3 — Twin Prime Pair (2^3 × origin ± 1)

2^3 × origin − 1

1.377 × 10⁹⁵(96-digit number)

13774655316599847074…82542396016073628559

Verify on FactorDB ↗Wolfram Alpha ↗

2^3 × origin + 1

1.377 × 10⁹⁵(96-digit number)

13774655316599847074…82542396016073628561

Verify on FactorDB ↗Wolfram Alpha ↗

Difference: 2^3 × origin + 1 − 2^3 × origin − 1 = 2 (twin primes ✓)

Level 4 — Twin Prime Pair (2^4 × origin ± 1)

2^4 × origin − 1

2.754 × 10⁹⁵(96-digit number)

27549310633199694148…65084792032147257119

Verify on FactorDB ↗Wolfram Alpha ↗

2^4 × origin + 1

2.754 × 10⁹⁵(96-digit number)

27549310633199694148…65084792032147257121

Verify on FactorDB ↗Wolfram Alpha ↗

Difference: 2^4 × origin + 1 − 2^4 × origin − 1 = 2 (twin primes ✓)

Level 5 — Twin Prime Pair (2^5 × origin ± 1)

2^5 × origin − 1

5.509 × 10⁹⁵(96-digit number)

55098621266399388297…30169584064294514239

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 Bi-Twin Chain. 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 TWN formula:

TWN: twin pairs (p, p+2) where p = origin/primorial − 1 and p+2 = origin/primorial + 1

Cross-reference on Chainz Explorer

Block #2,643,360

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