989898991 has 4 divisors (see below), whose sum is σ = 1006677000. Its totient is φ = 973120984.

The previous prime is 989898989. The next prime is 989898997. The reversal of 989898991 is 199898989.

989898991 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.

It is not a de Polignac number, because 989898991 - 2¹ = 989898989 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 989898991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (989898997) 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, 8388916 + ... + 8389033.

It is an arithmetic number, because the mean of its divisors is an integer number (251669250).

Almost surely, 2^989898991 is an apocalyptic number.

989898991 is a deficient number, since it is larger than the sum of its proper divisors (16778009).

989898991 is a wasteful number, since it uses less digits than its factorization.

989898991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16778008.

The product of its digits is 30233088, while the sum is 70.

The square root of 989898991 is about 31462.6602657817. The cubic root of 989898991 is about 996.6215962413.

The spelling of 989898991 in words is "nine hundred eighty-nine million, eight hundred ninety-eight thousand, nine hundred ninety-one".