I didn't state the number but I can pitch in: "G. F. KrivoÅejev, Soviet Casualties and Combat Losses in the Twentieth Century, 1997, ISBN 1-85367-280-7, Greenhill Books" states 126 875 dead or missing (estimate), 264 908 wounded and
3 100 prisoners. That's approximately 400 000 casualties. Additionally Kruschev said that 1.5 million men were sent to Finland and one million of them were killed. Although this is certainly an exaggeration it has a hint of truth since in reality, no one knows the numbers. The army was not organized, they were merely gathering men and sending them over to be slaughtered. Some people weren't even arranged to companies. For additional information I suggest William Trotter: Frozen Hell.