9998099981 has 4 divisors (see below), whose sum is σ = 9998651772. Its totient is φ = 9997548192.

The previous prime is 9998099927. The next prime is 9998100037. The reversal of 9998099981 is 1899908999.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1899908999 = 79 ⋅24049481.

It can be written as a sum of positive squares in 2 ways, for example, as 2514119881 + 7483980100 = 50141^2 + 86510^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-9998099981 is a prime.

It is a super-2 number, since 2×9998099981² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9998099081) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 247760 + ... + 285273.

It is an arithmetic number, because the mean of its divisors is an integer number (2499662943).

Almost surely, 2^9998099981 is an apocalyptic number.

It is an amenable number.

9998099981 is a deficient number, since it is larger than the sum of its proper divisors (551791).

9998099981 is a wasteful number, since it uses less digits than its factorization.

9998099981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 551790.

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

The square root of 9998099981 is about 99990.4994536981. The cubic root of 9998099981 is about 2154.2982324943.

The spelling of 9998099981 in words is "nine billion, nine hundred ninety-eight million, ninety-nine thousand, nine hundred eighty-one".