'Apostle' in the Bible

From Paul, called to be an apostle of Christ Jesus by the will of God, and Sosthenes, our brother,

Am I not free? Am I not an apostle? Have I not seen Jesus our Lord? Are you not my work in the Lord?

If I am not an apostle to others, at least I am to you, for you are the confirming sign of my apostleship in the Lord.

For I am the least of the apostles, unworthy to be called an apostle, because I persecuted the church of God.