The relation between the 22 letters of the Hebrew alphabet and the 22 books of the OT in the Alexandrian canon are also referred to by several other early Church Fathers, e.g, Hilary, Athanasius, Jerome, etc. As well as this there are the commentaries upon the symbolism of the number 22 mentioned in scriptural, pseudo-epigraphic and apocryphic sources, for example Jubilees 2:23 -BOUGEAREL Alain wrote: + Signification of the Number 22 by Origene
There (were) two and twenty heads of mankind from Adam to Jacob, and two and twenty kinds of work were made until the seventh day; this is blessed and holy; and the former also is blessed and holy; and this one serves with that one for sanctification and blessing.*
Jubilees 2: http://www.pseudepigrapha.com/jubilees/2.htm
*This fragment of Jubilees 2:1-23 was widely known in the East and West, in Greek and Latin, through quotations of it in for example Epiphanius, Justin Martyr, Origen, Diodorus of Antioch, Isidore of Alexandria, Isidore of Seville, Eutychius, Patriarch of Alexandria, John of Malala, Syncellus, Cedrenus and others.
For example, according to Epiphanius (Greek):
1. (1)Heaven, (2)earth, (3)water, (4)spirits, (5)abysses, (6) darkness, (7) light = 7
2. (8)Firmament. = 1
3. (9) the seas, the rivers, and the fountains and lakes, (10) seed, grains and plants, (11) fruit trees and those without fruit, and (12) forests (or paradise, gardens, the Garden of Eden). = 4
4. (13) the sun, (14) the moon, (15) the stars. = 3
5. (16) the great whales, (17) the fishes and the other creeping things in the waters, (18) the winged birds. = 3
6. (19) wild beasts, (20) cattle, (21) the creeping things of the earth, (22) man, the perfection of the World. = 4
And the latin text of Isidore of Seville, Etymologies, XVI, 26:10
10 ... Cuius numeri causa inde tracta est, eo quod in principio Deus viginti duo opera fecerit. Nam prima die septem opera fecit: id est materiam informem, angelos, lucem, caelos superiores, terram, aquam atque aerem. Secunda die firmamentum solum. Tertia die quattuor: maria, semina, sationes atque plantaria. Quarta die tria: solem, lunam et stellas. Quinta die tria: pisces et reptilia aquarum et volatilia. Sexta die quattuor: bestias, pecudes, reptilia terrae et hominem. Et facta sunt omnia viginti duo genera in diebus sex. Et viginti duae generationes sunt ab Adam usque ad Iacob, ex cuius semine nascitur omnis gens Israel; et viginti duo libri Veteris Testamenti usque ad Hester; et viginti duarum litterarum sunt elementa, quibus constat divinae legis doctrina.
10 ...The reason for the measure is because in the beginning God created twenty-two works. For the first day he created seven works, that is, formless matter, angels, the light, the upper heavens, the earth, water and air. The second day, the firmanent alone. The third day, four works: seas, seeds, sown fields and planted. On the fourth day, three works: the sun, the moon and the stars. The fifth day, three works: the fishes, and creeping things of the waters and the birds of the air. On the sixth day, four works: beasts, cattle, the creeping things of the earth and man. There were twenty-two kinds of all things created in six days. And twenty-two generations from Adam to the time of Jacob, from whose seed the nation of Israel was born; as there are the twenty-two books of the Old Testament, as far as Esther; and the twenty-two letters are the elements, of which the doctrines of divine law are composed.