One gigasecond is:
1,000,000,000 seconds
11574.074 days (1 day is 84,600 seconds)
31.688738506811430964562103462971 gregorian years (365.2425 days)
2 Gs = 63.377477013622861929124206925941 gregorian years
3 Gs = 95.066215520434292893686310388913 gregorian years
4 Gs = 126.75495402724572385824841385188 gregorian years