The unit that comes after trillion is a quadrillion, which is equivalent to 1,000 trillions. Numbers greater than 1,000 change units every three decimal places, equivalent to multiplying the base unit by 1,000. For example, a million is equal to 1,000 thousands.
The units for large numbers have different prefixes to specify their size. After the millions, names change based on Latin terms. For example, billion uses the prefix "bi", which is Latin for two, while trillion uses the prefix "tri," which is Latin for three. The logical extension for this pattern is to use the prefix associated with the Latin term for four, which is "quad."