989999989 has 4 divisors (see below), whose sum is σ = 1080000000.
Its totient is φ = 899999980.
The previous prime is 989999957. The next prime is 989999993.
It can be divided in two parts, 9 and 89999989, that added together give a palindrome (89999998).
989999989 is nontrivially palindromic in base 10.
989999989 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 Blum integer, because the two primes are equal to 3 mod 4.
It is not a de Polignac number, because 989999989 - 25 = 989999957 is a prime.
It is a Duffinian number.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (989999909) by changing a digit.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 44999989 + ... + 45000010.
It is an arithmetic number, because the mean of its divisors is an integer number (270000000).
Almost surely, 2989999989 is an apocalyptic number.
It is an amenable number.
989999989 is a deficient number, since it is larger than the sum of its proper divisors (90000011).
989999989 is a wasteful number, since it uses less digits than its factorization.
989999989 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 90000010.
The product of its digits is 306110016, while the sum is 79.
The square root of 989999989 is about 31464.2652703031.
The cubic root of 989999989 is about 996.6554897213.
The spelling of 989999989 in words is "nine hundred eighty-nine million, nine hundred ninety-nine thousand, nine hundred eighty-nine".