Convert from electron to arroba [Spain]

Unit Definition (electron)
The electron is the mass of the electron, often used as a unit of mass in particle physics. An electron has a mass of about 9.109 382 x 10E-31 kilogram, 9.109 382 x 10E-28 gram, or 0.510 9989 million electronvolts.

Unit Definition (arroba [Spain])
The arroba [Spain] is a traditional unit of weight in Spain and Portugal, equal to 1/4 quintal. However, the Spanish and Portuguese quintals are of different sizes. In Spain, the arroba equals 25.36 pounds (11.50 kilograms); arrobas of very similar sizes were established in the Spanish speaking countries of Latin America. The arroba has also been used as a metric unit equal to exactly 15 kilograms. The name of the unit comes from ar rub', Arabic for "the quarter."