Is 2.121121 1 1 2 1 1 1 1 2 and irrational number?

The number 2.121121... is a repeating decimal, specifically 2.121, which repeats the sequence "121" indefinitely. Since it can be expressed as a fraction (specifically, it can be written as a rational number), it is not an irrational number. Irrational Numbers cannot be expressed as a fraction of two integers and have non-repeating, non-terminating decimal expansions. Therefore, 2.121121... is a rational number.