A long time

80,000 * 80,000 *250 = 1,600,000 blocks
1,600,000 * 50ms = 80,000,000,000,000 (80 trillion milliseconds)
80,000,000,000,000 / 1000 = 80,000,000,000 seconds
80,000,000,000 / 60 = 1,333,333,333.333 (about 1.3 billions minutes)
/ 60 = 22,222,222.22 hours
/24 = 925,925.9 days
/365.25 = 2,535 years