utm - Transform from WGS84 to EPSG 3785 (google maps)

I am a Java Developer and I was given this coordinates from a database

verbat_sistema_coordenadas  verbatim_SRS    datum   verbat_longitud verbat_latitud
UTM                         WGS84           WGS84   9947921          815887

And I tried the examples here https://stackoverflow.com/questions/7661/java-code-for-wgs84-to-google-map-position-and-back, but I get something like this when I try to use the MercatorTransform showed there

LatVerb           LonVerb               LatEPSG                        LonEPSG
815612.0         9948458.0           7.3267672551129115        66.40190209729147

I tried the formulas shown there and I get differnt result with each formula and none are close to what I need. Then someone I am working with gave me an excel sheet with some formulas but the have a million variables and constants

Fi' Ni  a   A1  A2  J2  J4  J6  Alfa    Beta    Gamma   B(fi)   b   Zeta    Xi  Eta Sen h Xi    Delta Lambda    Tau

And they depend on the Timezone(meridian, maybe I am translating this wrong?), and the hemisphere, and they seem to work. They gave me -0.4544682953,-78.1736736245, which is the correct answer.

This is the excel sheet http://www.gabrielortiz.com/descargas/descarga.asp?Fichero=Conversion_UTM_Geograficas.xls

I tried using geotools, but it was way off too http://osgeo-org.1560.x6.nabble.com/convert-wgs84-coordinate-to-Google-Map-coordinate-system-EPSG-3785-with-geotools-and-java-td4983362.html