db.r4.4xlarge is an Amazon DocumentDB size with 16 vCPUs, 122 GiB memory (Intel Xeon E5-2686 v4 (Broadwell)). In US East (N. Virginia) it costs $2.216 per hour on demand ($1,617.68 per month) for Standard storage. It is sold in 4 regions.
Prices by region
USD per hour, Standard storage. Reserved prices are no upfront, standard. Cheapest on-demand first.