9990981 has 48 divisors (see below), whose sum is σ = 19393920. Its totient is φ = 4786560.

The previous prime is 9990961. The next prime is 9990989. The reversal of 9990981 is 1890999.

It is not a de Polignac number, because 9990981 - 2⁵ = 9990949 is a prime.

It is a super-2 number, since 2×9990981² = 199639402684722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9990989) by changing a digit.

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, 8455 + ... + 9563.

It is an arithmetic number, because the mean of its divisors is an integer number (404040).

Almost surely, 2^9990981 is an apocalyptic number.

9990981 is a gapful number since it is divisible by the number (91) formed by its first and last digit.

It is an amenable number.

9990981 is a deficient number, since it is larger than the sum of its proper divisors (9402939).

9990981 is a wasteful number, since it uses less digits than its factorization.

9990981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1146 (or 1143 counting only the distinct ones).

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

The square root of 9990981 is about 3160.8513093785. The cubic root of 9990981 is about 215.3786800333.

The spelling of 9990981 in words is "nine million, nine hundred ninety thousand, nine hundred eighty-one".