26,990 is spoken / written as twenty-six thousand, nine hundred and ninety (or sometimes just twenty-six thousand nine hundred ninety).
Work Step by Step
Read left to right. 26,990 has five places, so the number's highest value place is in the ten-thousands. So you say twenty-six thousand, nine hundred and ninety, since the ten-thousands place contains the digits 26 and the hundreds place contains 990.