990000000 has 384 divisors, whose sum is σ = 3884755680. Its totient is φ = 240000000.

The previous prime is 989999993. The next prime is 990000023. The reversal of 990000000 is 99.

It is a tau number, because it is divible by the number of its divisors (384).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.

It is a nialpdrome in base 10.

It is a zygodrome in base 10.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 89999995 + ... + 90000005.

Almost surely, 2^990000000 is an apocalyptic number.

990000000 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 990000000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1942377840).

990000000 is an abundant number, since it is smaller than the sum of its proper divisors (2894755680).

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

990000000 is an frugal number, since it uses more digits than its factorization.

990000000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66 (or 21 counting only the distinct ones).

The product of its (nonzero) digits is 81, while the sum is 18.

The square root of 990000000 is about 31464.2654451045. The cubic root of 990000000 is about 996.6554934126.

Adding to 990000000 its reverse (99), we get a palindrome (990000099).

990000000 divided by its reverse (99) gives a 7-th power (10000000 = 10⁷).

It can be divided in two parts, 9 and 90000000, that added together give a palindrome (90000009).

The spelling of 990000000 in words is "nine hundred ninety million", and thus it is an aban number.