its 57 megatonnes, or 57,000,000 tonnes of TNT. it was originally supposed to be 100MT but they scaled it back for fear of killing the pilots who dropped it. As it was, they air detonated it, dropped by parachute. The pilots (senior soviet officials) barely made it out alive. The fallout cloud went around the earth THREE times, and on its third pass was still large enough to be measured.
Notice
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