ro.build.version.sdk=21 Means your android version is Android 5.1 Lollipop ro.build.version.sdk=Arm64 Means your android architecture is Arm64 / 64bit
ro.build.version.sdk=22 Means your android version is Android 6.0 Marshmallow ro.build.version.sdk=armeabi-v7a,armeabi. Means your android architecture is Arm32 / 32bit