9909998981 has 2 divisors, whose sum is σ = 9909998982. Its totient is φ = 9909998980.

The previous prime is 9909998977. The next prime is 9909999019. The reversal of 9909998981 is 1898999099.

9909998981 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 8778753025 + 1131245956 = 93695^2 + 33634^2 .

It is a cyclic number.

It is not a de Polignac number, because 9909998981 - 2² = 9909998977 is a prime.

It is a super-3 number, since 3×9909998981³ (a number of 31 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9909998381) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4954999490 + 4954999491.

It is an arithmetic number, because the mean of its divisors is an integer number (4954999491).

Almost surely, 2^9909998981 is an apocalyptic number.

It is an amenable number.

9909998981 is a deficient number, since it is larger than the sum of its proper divisors (1).

9909998981 is an equidigital number, since it uses as much as digits as its factorization.

9909998981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 34012224, while the sum is 71.

The square root of 9909998981 is about 99548.9777998750. The cubic root of 9909998981 is about 2147.9518248931.

The spelling of 9909998981 in words is "nine billion, nine hundred nine million, nine hundred ninety-eight thousand, nine hundred eighty-one".