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Which three isotopes occur naturally in potassium?

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A periodic table element box for potassium shows atomic number 19, symbol K, atomic weight 39.0983, electron configuration [Ar]4s1, and name potassium. Icons indicate it is an alkali metal, solid at room temperature, body-centered cubic crystal structure, and has strongly basic higher-valence oxides. A key explains the symbols for alkali metals, solid state, body-centered cubic structure, and strong basicity. — potassium Properties of potassium.

Natural potassium consists of three isotopes:

Potassium-39: 93.26 percent
Potassium-41: 6.73 percent
Potassium-40: Approximately 0.01 percent1

Potassium-40 is a radioactive isotope with a half-life of $10^{9}$ years, and its decay is utilized in potassium-argon dating to determine the age of rocks and minerals.12