9900900891 has 32 divisors (see below), whose sum is σ = 16870254080. Its totient is φ = 5621604768.

The previous prime is 9900900881. The next prime is 9900900907. The reversal of 9900900891 is 1980090099.

It is not a de Polignac number, because 9900900891 - 2⁹ = 9900900379 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (9900900881) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 137161 + ... + 196506.

It is an arithmetic number, because the mean of its divisors is an integer number (527195440).

Almost surely, 2^9900900891 is an apocalyptic number.

9900900891 is a deficient number, since it is larger than the sum of its proper divisors (6969353189).

9900900891 is a wasteful number, since it uses less digits than its factorization.

9900900891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 333840 (or 333834 counting only the distinct ones).

The product of its (nonzero) digits is 52488, while the sum is 45.

The square root of 9900900891 is about 99503.2707552872. The cubic root of 9900900891 is about 2147.2942990108.

The spelling of 9900900891 in words is "nine billion, nine hundred million, nine hundred thousand, eight hundred ninety-one".