Secret of the Number Seven

Why is the circumambulation, the walk back and forth between al-Safa and al-Marwa and the stoning of the Jamarat during pilgrimage all performed seven times? And why is the number of the days of the week and the number of the skies and the earths seven? And prostration during prayer is on seven bones, and the oft-repeated verses are seven and covenants of Solomon are seven as well.