The part number is CAP CER 820PF 1KV C0G/NP0 1825. This refers to a ceramic capacitor with a capacitance of 820 pF and an operating voltage of 1000V (1kV). It belongs to the C0G, NP0 (also known as 1B) classification and has a metric size designation of 1825 (4564 in the metric system).