9800999981 has 2 divisors, whose sum is σ = 9800999982. Its totient is φ = 9800999980.

The previous prime is 9800999947. The next prime is 9801000023. The reversal of 9800999981 is 1899990089.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7672008100 + 2128991881 = 87590^2 + 46141^2 .

It is an emirp because it is prime and its reverse (1899990089) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 9800999981 - 2²² = 9796805677 is a prime.

It is a super-2 number, since 2×9800999981² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9800999921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4900499990 + 4900499991.

It is an arithmetic number, because the mean of its divisors is an integer number (4900499991).

Almost surely, 2^9800999981 is an apocalyptic number.

It is an amenable number.

9800999981 is a deficient number, since it is larger than the sum of its proper divisors (1).

9800999981 is an equidigital number, since it uses as much as digits as its factorization.

9800999981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3779136, while the sum is 62.

The square root of 9800999981 is about 98999.9999040404. Note that the first 4 decimals coincide. The cubic root of 9800999981 is about 2140.0477455356.

The spelling of 9800999981 in words is "nine billion, eight hundred million, nine hundred ninety-nine thousand, nine hundred eighty-one".