About block 3,644
Bitcoin block 3,644 was mined by Unknown on February 9, 2009 at 5:16 PM UTC, 4 min 25 s after block 3,643. That is faster than the 10-minute average the network aims for: blocks come in bursts because finding one is pure chance.
It confirmed 1 transactions in 0.00 MB (0.0% of the 4 million weight-unit limit). The median transaction paid 0.00 sat/vB, and all fees added up to 0.0000 BTC. With the 50.000 BTC subsidy of halving era 1, Unknown earned 50.0000 BTC for this block.
Block 3,644 is number 1,629 of 2,016 in difficulty epoch 1; 387 blocks remain until the next difficulty adjustment at block 4,031. The next halving is at block 210,000, 206,356 blocks after this one.
Its hash starts with 8 zeros: that is the proof of work, a number below the target that the whole network’s hashrate had to search for. Unknown found 16 blocks in the week before. Today the block has 970,426 confirmations, so it is settled beyond any practical doubt.