The notation is ₅₅¹³⁷Cs. The Cs represents the chemical symbol of Caesium element. The subscript number at the left hand side of the symbol indicates the atomic number. Hence, atomic number of Cs is 55. The superscript number at the left hand side of the symbol shows the mass number. Hence, the mass number of the Cs is 137.
I didn't know if you meant to the power of 14 but if you did here your answer: 3.64 x 10^-19 (you just multiply the frequency by Planck's constant= 6.63 × 10^–34)
