Stroke count: 18
Meaning: bottom, base, slap, bang, all of a sudden
Kunyomi: はた はたと
Onyomi: トウ
Composition: 石 當
Radical: 石
Meaning: stone
礑と （はたと） suddenly (hit), with a slap, sharply (glance, glare, etc.), fiercely, suddenly, all of a sudden, in a flash, completely, totally, utterly