Dionysius the Areopagite - Celestial Hierarchy - The number of Intelligences
Type of Spiritual Experience
How many Intelligences are there? Well if there is an Intelligence for every type of entity ever created there must be millions upon millions – there are nearly a million known types of insects, over 300,000 species of plant, thousands upon thousands of animals, and millions of types of micro-organism..
More than one source here but I have grouped them because the observations are related.
A description of the experience
Revelation 5 (King James Version)
11And I beheld, and I heard the voice of many angels round about the throne and the beasts and the elders: and the number of them was ten thousand times ten thousand, and thousands of thousands;
The Book of Enoch
14.22 The flaming fire was round about Him and a great fire stood before Him and none around could draw nigh Him ten thousand times ten thousand stood before Him, yet He needed no counsellor
Dionysius – the Celestial Hierarchy
This is also worthy, I think, of intellectual consideration, that the scriptural tradition respecting Angels gives their number as thousands of thousands and ten thousand times ten thousand, multiplying and repeating the very highest numbers we have, thus clearly showing that the Orders of the Celestial beings are innumerable for us; so many are the blessed Hosts of the Supermundane Intelligences, wholly surpassing the feeble and limited range of our material numbers. And they are definitely known only by their own supermundane and celestial Intellect and the knowledge which is granted to them all bounteously by the All-knowing Mother wisdom of the most high God, which is superessentially at once the substantial cause, the connecting power, and the universal consummation of all principles and things