It is given that the units place digit is 3.

So, let tens place digit be y.

∴ Our number = (10y + 3) …(1)

Our given condition is that seven times the sum of the digits is the number itself.

∴ By given condition,

7(y + 3) = (10 y + 3)
7 y + 21 = 10 y + 3
∴ 10 y - 7y = 21 - 3
∴ 3 y = 18
∴ y = 6

Substituting the value of y in equation1,

Number = 10 × 6 + 3 = 63

Hence, required number is 63.