That prize she won is the maximum value of an unsigned 32 bit value. Basically, some 32 bit location was set to 0xFFFFFFFF or 11111111111111111111111111111111 . It’s a bug.
My bet is that the team of programmers were leftovers from the pool of Obamacare developers and were tasked with developing the payout routine in 3 years for 420M dollars.
Should mention that you need to remove the decimal point. After you remove the decimal point, the number is 2 to the 32 power -1.