About block 12,721
Bitcoin block 12,721 was mined by Unknown on April 30, 2009 at 3:23 AM UTC, 3 min 28 s after block 12,720. 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 12,721 is number 626 of 2,016 in difficulty epoch 6; 1,390 blocks remain until the next difficulty adjustment at block 14,111. The next halving is at block 210,000, 197,279 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 2 blocks in the week before. Today the block has 962,977 confirmations, so it is settled beyond any practical doubt.