[Seven_0]

No, it was not "discovered" in the 19th century --> the early Christians wrote of the significance of the number 7 as the number for completeness

The number seven is the most conspicuous of all the numbers and the meaning is easily discerned. The meaning of all the other numbers can be found on much less traveled path. I am not aware of any study of the numerical structure of scripture before the late nineteenth century.

[Cronos]

“I am not aware of any study of the numerical structure of scripture before the late nineteenth century.”

I take it you haven’t read Irenaeus ( c. 130 – c. 202 AD)?
https://www.newadvent.org/cathen/08130b.htm

Or St. Ambrose (c. 339 – c. 397)?
https://www.newadvent.org/cathen/01383c.htm

Ambrose wrote
“The number seven is good, but we do not explain it after the doctrine of Pythagoras and the other philosophers, but rather according to the manifestation and division of the grace of the Spirit; for the prophet Isaias has enumerated the principal gifts of the Holy Spirit as seven”