Effective annual rate

Hi Sir,
I hope you are well.

Please may you elaborate this question and answer a little for me.
What is the effective annual rate of interest of 2.1% compounded every three month?
Answer is 8.67%

My take on this question was to convert nominal rate (2.1%) to effective annual rate by applying this formula (1 + i/m) ^ m – 1. Where ‘m’ is the number of compound periods
‘i’ is the interest rate
Applying this formula my answer isn`t correct.

Please advise.

Many Thanks