999999999999

is the integer between.

Math features
999999999999 = 1012 - 1.
 * 999999999999 is an odd number.
 * 999999999999 is a composite number and an abundant number.
 * 999999999999 is 1 less than a power of 10. So,
 * 999999999999 has 28 factors (256).
 * 999999999999 is the one millionth member of the form n² - 1.