AGE really is nothing but a number, just ask MADONNA. The pop queen continues to defy her years, both looks and lifestyle-wise. Last night her Madgesty showed new toyboy BRAHIM ZAIBAT the delights of London, starting with nightclub Aura. Baby faced Brahim - who bares a slight similarity to JLS star ASTON MERRYGOLD - is 20 years younger than 52-year-old Madonna. Her last fella, JESUS LUZ, is 24.