Although this peak was apparently surveyed at 13,588' for the old Mt. Whitney 15' USGS quadrangle, the new Mt. Brewer 15' has only the 4120m contour surrounding it. The Mt. Brewer USGS 10m Digital Elevation Model puts the summit at 4125m (13,533'), so that's likely closer to the actual summit elevation.
"After the first glass, you see things as you wish they were. After the second, you see things as they are not. Finally, you see things as they really are, which is the most horrible thing in the world."
--Oscar Wilde on Absinthe