New high-precision photometric measurements of the eclipsing star V839 Cep (P=9.96-day, V(A+B)=9.64mag, e=0.07, B6 V + B7 V), which is the A component of the visual double star J21035+5925AB, have established that component B is also an eclipsing variable (P=4.075-days, B9 V + G8 V). For component A, the apsidal rotation rate was measured to be dw/dt=0.028deg/year, which exceeds the theoretical value under the condition of synchronism dw/dt=0.021 deg/year. The physical parameters of the component stars of the eclipsing pair "A" were obtained: T1=13200+/-300K, M1=(3.7+/-0.15)M_{sun}_, R1=(2.57+/-0.05)R_{sun}_, T2=11900+/-250K, M2=(3.2+/-0.15)M_{sun}_, R2=(2.42+/-0.05)R_{sun}_, and components of the eclipsing pair B: T1=10600+/-200K, M1=(2.6+/-0.2)M_{sun}_, R1=(1.97+/-0.05)R_{sun}_, T2=5540+/-50K, M2=(0.88+/-0.05)M_{sun}_, R2=(0.84+/-0.05)R_{sun}_ The age of the system is determined to be 70 Myr with solar chemical composition. The components of star "A" are pulsating variable stars of the slow Beta Cephei (SBC) type.