functions - How to apply `Length` in all elements

I want to apply Length in each element from a list. For example:

My list is: {1,{2,3},{4,5,6}}

How to apply Length in each element of this list?

Length[{1}]
Length[{2,3}]
Length[{4,5,6}] 

I have tried to use Thread, but doesn't works:

In[235]:= Thread[Length[{1, {2, 3}, {4, 5, 6}}]]


Out[235]= 3

The result that I want is some like:

1
2
3

Which is the number of elements in each element.

Answer

If[AtomQ @ #, 1, Length @ #] & /@ {1, {2, 3}, {4, 5, 6}}

{1, 2, 3}

If the input list does not contain {} (thanks: @corey979), you can also use:

Length /@ {1, {2, 3}, {4, 5, 6}} /. 0 -> 1
(* or Map[Length]@{1, {2, 3}, {4, 5, 6}} /. 0 -> 1 *)

{1, 2, 3}