The Otyugh description reads:
Attack: Melee 3 (one creature); +12 vs. AC
The way I read it due to it mentioning "one creature" that its 3 attacks per standard action. Is this correct?
That 3 is actually it's melee reach.
A multi attack stat block in 4e looks like:
When you see a power say melee X, the X refers to the reach of the attack. melee 1 is the default, but you might see 0, 2, 3, or more.