Question: Who is Philip, Prince Of Anhalt-Köthen's paternal grandfather?

Context paragraphs:
title: Adolph I, Prince of Anhalt-Köthen
paragraph_text: Adolph I, Prince of Anhalt- Köthen( died Zerbst, 28 August 1473), was a German prince of the House of Ascania and ruler of the principality of Anhalt- Köthen. He was the eldest son of Albert IV, Prince of Anhalt- Köthen, by his first wife Elisabeth, daughter of Gebhard III, Count of Mansfeld.
title: Augustus Christian Frederick, Duke of Anhalt-Köthen
paragraph_text: Augustus Christian Frederick of Anhalt-Köthen (Köthen, 18 November 1769 – Schloss Geuz, 5 May 1812), was a German prince of the House of Ascania, ruler of the principality of Anhalt-Köthen, and from 1806 the first "Duke of Anhalt-Köthen." He was the eldest son of Karl George Lebrecht, Prince of Anhalt-Köthen, by his wife Louise Charlotte, daughter of Frederick, Duke of Schleswig-Holstein-Sonderburg-Glücksburg.
title: Waldemar VI, Prince of Anhalt-Köthen
paragraph_text: Waldemar VI, Prince of Anhalt-Köthen (1450 – Köthen, 1 November 1508), was a German prince of the House of Ascania and ruler of the principality of Anhalt-Köthen. He was the eldest son of George I, Prince of Anhalt-Dessau, by his second wife Sophie, possibly a member of the House of Hohnstein.
title: Albert VI, Prince of Anhalt-Köthen
paragraph_text: Albert VI, Prince of Anhalt- Köthen( died 9 January 1475) was a German prince of the House of Ascania and ruler of the principality of Anhalt- Köthen. He was the youngest son of Albert IV, Prince of Anhalt- Köthen, but the eldest child of his second wife Elisabeth, daughter of Gebhard XI, Count of Querfurt.
title: William Louis, Prince of Anhalt-Köthen
paragraph_text: William Louis of Anhalt- Köthen( 3 August 1638, in Köthen – 13 April 1665, in Köthen), was a German prince of the House of Ascania and ruler of the principality of Anhalt- Köthen. He was the second son of Louis I, Prince of Anhalt- Köthen, but second- born son of his second wife Sophie, daughter of Simon VI, Count of Lippe.
title: Augustus Louis, Prince of Anhalt-Köthen
paragraph_text: Augustus Louis of Anhalt- Köthen( 9 June 1697 in Köthen – 6 August 1755 in Köthen), was a German prince of the House of Ascania and ruler of the principality of Anhalt- Köthen. He was the third( second surviving) son of Emmanuel Lebrecht, Prince of Anhalt- Köthen, by his wife Gisela Agnes of Rath.
title: Philip, Prince of Anhalt-Köthen
paragraph_text: Philip, Prince of Anhalt-Köthen (31 May 1468 – 13 November 1500) was a German prince of the House of Ascania and ruler of the principality of Anhalt-Köthen. He was the only son of Albert VI, Prince of Anhalt-Köthen, by his wife Elisabeth, daughter of Günther II, Count of Mansfeld.
title: Waldemar V, Prince of Anhalt-Köthen
paragraph_text: Waldemar V, Prince of Anhalt- Köthen( died 1436) was a German prince of the House of Ascania and ruler of the principality of Anhalt- Köthen. He was the second son of Albert IV, Prince of Anhalt- Köthen, by his first wife Elisabeth, daughter of Gebhard III, Count of Mansfeld.
title: Magnus, Prince of Anhalt-Köthen
paragraph_text: Magnus, Prince of Anhalt- Köthen( 1455 – 29 October 1524) was a German prince of the House of Ascania and ruler of the principality of Anhalt- Köthen. He was the third( but eldest surviving) son of Adolph I, Prince of Anhalt- Köthen, by his wife Cordula, daughter of Albert III, Count of Lindau- Ruppin.
title: Emmanuel Lebrecht, Prince of Anhalt-Köthen
paragraph_text: Emmanuel Lebrecht of Anhalt-Köthen (Köthen, 20 May 1671 – Köthen, 30 May 1704), was a German prince of the House of Ascania and ruler of the principality of Anhalt-Köthen. He was the only child of Emmanuel, Prince of Anhalt-Köthen, by his wife Anna Eleonore, daughter of Henry Ernest, Count of Stolberg.

Reasoning steps:
Philip, Prince of Anhalt-Köthen father Albert VI, Prince of Anhalt-Köthen
Albert VI, Prince of Anhalt-Köthen father Albert IV, Prince of Anhalt-Köthen

Answer: spans: Albert IV, Prince of Anhalt-Köthen