Blackjack
Not a point more, not a point less — exactly 21.
A number whose digits sum to exactly 21, like 777 (7+7+7=21) or 678 (6+7+8=21). Blackjack at the card table; the same perfect hit among numbers.
Your record
There are 39,662 blackjacks in range, 3.97%, about 1 in 25 — sounds common, but this is already mid-bell-curve territory. Six-digit digit sums average 27; sitting 6 points off center, 21 slides from the 5.5% peak down to roughly 4%.
The choice of 21 is a poker-table tribute, of course, but 21 has its own mathematical temperament: two-digit numbers can never reach it (9+9=18 max), three-digit numbers barely start (smallest is 399), and six digits is where blackjack truly plays.
The most on-theme example is 777: the slot-machine jackpot whose digits sum to exactly 21 — two gambling icons meeting in one string, with a triple thrown in for free.