9999000000 has 588 divisors, whose sum is σ = 39468713544. Its totient is φ = 2400000000.

The previous prime is 9998999977. The next prime is 9999000001. The reversal of 9999000000 is 9999.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nialpdrome in base 10.

It is a zygodrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9999000001) by changing a digit.

It is a polite number, since it can be written in 83 ways as a sum of consecutive naturals, for example, 98999950 + ... + 99000050.

Almost surely, 2^9999000000 is an apocalyptic number.

9999000000 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 9999000000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (19734356772).

9999000000 is an abundant number, since it is smaller than the sum of its proper divisors (29469713544).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

9999000000 is a wasteful number, since it uses less digits than its factorization.

9999000000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 160 (or 122 counting only the distinct ones).

The product of its (nonzero) digits is 6561, while the sum is 36.

The square root of 9999000000 is about 99994.9998749937. Note that the first 3 decimals coincide. The cubic root of 9999000000 is about 2154.3628731483.

Adding to 9999000000 its reverse (9999), we get a palindrome (9999009999).

Multiplying 9999000000 by its reverse (9999), we get a square (99980001000000 = 9999000²).

9999000000 divided by its reverse (9999) gives a 6-th power (1000000 = 10⁶).

It can be divided in two parts, 99 and 99000000, that multiplied together give a square (9801000000 = 99000²).

The spelling of 9999000000 in words is "nine billion, nine hundred ninety-nine million", and thus it is an aban number.