What is the equation relating radius of curvature and the value $(1-Omega)$?

I get that $(1 – Omega) = Omega_k$.

What I used to know, but have forgotten and cannot find is

what is the equation relating $R_{curv}$ (radius of curvature) and $Omega_k$?

I have found the answer to this question before, but now that I want to work with it again, I seem to have misplaced it, and I am unable to find it. What I remember be is that

$R_{curv}$ = A $sqrt {frac {-1} {Omega_k}}$,

where A is the coefficient whose value I would like to know in units of meters.

ADDED

I found the answer in

https://arxiv.org/abs/1911.02087

page 2. The answer is A = c/$H_0$.
The value given for the curvature density is $Omega_k$~-0.1.
The value given for the radius of curvature is $R_{curv}$~10Gpc~33Gly.

Note that if $Omega_k$>0, the value of $R_{curv}$ is imaginary.