A parcel number is the land “identification” number for the piece of land provided by the county or some governmental body.  It typically shows up on the property tax statement. 

It's the APN number assigned by the assessors office in the county the property is in.

The Title Company should have included that on the F 593.

You "might" be able to fool the system with all 999999999999999999999999999999999999's

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Or do some searching for the legal description of the property or find it in the other escrow documents, but it should be where it is intended to be in section I circled.