Subtracting 8999999 from its reverse (9999998), we obtain a palindrome (999999).
8999999 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.
It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 9999998 = 2 ⋅4999999.
It is a cyclic number.
It is a Duffinian number.
It is a plaindrome in base 10.
It is a congruent number.
Almost surely, 28999999 is an apocalyptic number.
8999999 is a wasteful number, since it uses less digits than its factorization.
8999999 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 6000.
The square root of 8999999 is about 2999.9998333333. Note that the first 3 decimals coincide. The cubic root of 8999999 is about 208.0083746012.
The spelling of 8999999 in words is "eight million, nine hundred ninety-nine thousand, nine hundred ninety-nine".