How to calculate minutes/100 yards

I must be doing it wrong because what I calculate for minutes/100 yards on a race is always different than what the results list for my pace.

For instance, today I did a half iron-man swim in 35:34. My math says:

35:34 = 35.566s (34/60 = .566, formatting the seconds as a decimal)
1.2 mi = 2100 y = 21 (100 yard units)

minutes / 100y = 35.566 (minutes) / 21 (100 yard units)
= 1.69 minutes/100y (1:41 formatted as minute:second instead of a decimal)

The results list my pace as 1:59. That seems wrong even with just a high level view. If I swam roughly 2 minutes per 100 yards, then it would take me 42 minutes to swim 2100 yard, which is longer than my time.

So maybe the swim wasn't 2100 yards? If I solve for yards assuming I swam 1:59m/100y for 35.5 minutes, that means the swim was 1775y. That's too short for 1.2 mi and the race directory said it was spot on 1.2 mi.

Am I doing math wrong!??!