Hm, if we divide $2.4 T by $121,000 we arrive at ~ BTC 19.8 M --> so I guess they used the total number of mined BTC, _including_ those millions of coins that are hopefully never going to be moved again. Oh well, Satoshi's coins are currently worth ~ 1,100,000 x $121,000 = $0.13 T .. So excluding these coins would still land BTC at $2.27 T market cap .. not that big of a difference.