999981000090 has 384 divisors, whose sum is σ = 2881299133440. Its totient is φ = 239575449600.

The previous prime is 999981000059. The next prime is 999981000103. The reversal of 999981000090 is 90000189999.

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 1002989472 + ... + 1002990468.

It is an arithmetic number, because the mean of its divisors is an integer number (7503383160).

Almost surely, 2^999981000090 is an apocalyptic number.

999981000090 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is a pronic number, being equal to 999990×999991.

It is a practical number, because each smaller number is the sum of distinct divisors of 999981000090, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1440649566720).

999981000090 is an abundant number, since it is smaller than the sum of its proper divisors (1881318133350).

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

999981000090 is a wasteful number, since it uses less digits than its factorization.

999981000090 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1398 (or 1395 counting only the distinct ones).

The product of its (nonzero) digits is 472392, while the sum is 54.

The spelling of 999981000090 in words is "nine hundred ninety-nine billion, nine hundred eighty-one million, ninety", and thus it is an aban number.