A day is as a thousand years and thousand years is as a day....................
2 Peter 3:8
New International Version
8 But do not forget this one thing, dear friends: With the Lord a day is like a thousand years, and a thousand years are like a day.
A day as a thousand years. 365 days x 1000 = 365,000 years. 365,000 x 4000 years = 1,460,000,000 years. Almost one and a half billion years; Peter was preaching the right ballpark figure.