999989989 has 8 divisors (see below), whose sum is σ = 1021097880. Its totient is φ = 979082496.

The previous prime is 999989981. The next prime is 999990011. The reversal of 999989989 is 989989999.

It can be written as a sum of positive squares in 4 ways, for example, as 11390625 + 988599364 = 3375^2 + 31442^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 999989989 - 2³ = 999989981 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 (999989981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 39994 + ... + 59995.

It is an arithmetic number, because the mean of its divisors is an integer number (127637235).

Almost surely, 2^999989989 is an apocalyptic number.

It is an amenable number.

999989989 is a deficient number, since it is larger than the sum of its proper divisors (21107891).

999989989 is a wasteful number, since it uses less digits than its factorization.

999989989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 100199.

The product of its digits is 306110016, while the sum is 79.

The square root of 999989989 is about 31622.6183134794. The cubic root of 999989989 is about 999.9966629889.

The spelling of 999989989 in words is "nine hundred ninety-nine million, nine hundred eighty-nine thousand, nine hundred eighty-nine".