Block #209,478

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.

4.479 × 10¹⁰²(103-digit number)

44796015717823923307…39382333395315082239

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

4.479 × 10¹⁰²(103-digit number)

44796015717823923307…39382333395315082239

Verify on FactorDB ↗Wolfram Alpha ↗

origin + 1

4.479 × 10¹⁰²(103-digit number)

44796015717823923307…39382333395315082241

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

8.959 × 10¹⁰²(103-digit number)

89592031435647846615…78764666790630164479

Verify on FactorDB ↗Wolfram Alpha ↗

2^1 × origin + 1

8.959 × 10¹⁰²(103-digit number)

89592031435647846615…78764666790630164481

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

1.791 × 10¹⁰³(104-digit number)

17918406287129569323…57529333581260328959

Verify on FactorDB ↗Wolfram Alpha ↗

2^2 × origin + 1

1.791 × 10¹⁰³(104-digit number)

17918406287129569323…57529333581260328961

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

3.583 × 10¹⁰³(104-digit number)

35836812574259138646…15058667162520657919

Verify on FactorDB ↗Wolfram Alpha ↗

2^3 × origin + 1

3.583 × 10¹⁰³(104-digit number)

35836812574259138646…15058667162520657921

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

7.167 × 10¹⁰³(104-digit number)

71673625148518277292…30117334325041315839

Verify on FactorDB ↗Wolfram Alpha ↗

What this block proved

The miner who found this block proved the existence of 9 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

CommonChain length 9

Found in most blocks. The baseline for Primecoin's proof-of-work.

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