1 millennium = 31,536,000,000 s ÷ 2,461,600,000 s per human lifespan = 12.81 → 13

• ~78 years

1 millennium = 31,536,000,000 s ÷ 126,144,000 s per Olympiad = 250 → 250

• four years between Games

1 millennium = 31,536,000,000 s ÷ 88,775 s per Martian sol = 355200 → 355,235

• a day on Mars

1 millennium = 31,536,000,000 s ÷ 315,360,000 s per decade = 100 → 100

• en.wikipedia.org

1 millennium = 31,536,000,000 s ÷ 788,400,000 s per generation = 40 → 40

• ~25 years