bit more info, normalizing the geometry doesn't update it...
before normalizing to central meridian...
envelope
{-6217054.07748237,3083200.58936723,19742372.9881015,13268766.2816879}
base {ESRI.ArcGIS.Client.Geometry.Geometry}: {-6217054.07748237,3083200.58936723,19742372.9881015,13268766.2816879}
Extent: {-6217054.07748237,3083200.58936723,19742372.9881015,13268766.2816879}
Height: 10185565.692320695
Width: 25959427.065583907
XMax: 19742372.988101542
xmax: 19742372.988101542
xmin: -6217054.077482366
XMin: -6217054.077482366
ymax: 13268766.281687925
YMax: 13268766.281687925
YMin: 3083200.58936723
ymin: 3083200.58936723
after normalizing to central meridian...
normalizedEnvelope
{-6217054.07748237,3083200.58936723,19742372.9881015,13268766.2816879}
[ESRI.ArcGIS.Client.Geometry.Envelope]: {-6217054.07748237,3083200.58936723,19742372.9881015,13268766.2816879}
Extent: {-6217054.07748237,3083200.58936723,19742372.9881015,13268766.2816879}
GeometryChanged: null
SpatialReference: {ESRI.ArcGIS.Client.Geometry.SpatialReference}