9888998921 has 2 divisors, whose sum is σ = 9888998922. Its totient is φ = 9888998920.

The previous prime is 9888998887. The next prime is 9888998929. The reversal of 9888998921 is 1298998889.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5011932025 + 4877066896 = 70795^2 + 69836^2 .

It is a cyclic number.

It is not a de Polignac number, because 9888998921 - 2¹⁰ = 9888997897 is a prime.

It is not a weakly prime, because it can be changed into another prime (9888998929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4944499460 + 4944499461.

It is an arithmetic number, because the mean of its divisors is an integer number (4944499461).

Almost surely, 2^9888998921 is an apocalyptic number.

It is an amenable number.

9888998921 is a deficient number, since it is larger than the sum of its proper divisors (1).

9888998921 is an equidigital number, since it uses as much as digits as its factorization.

9888998921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 53747712, while the sum is 71.

The square root of 9888998921 is about 99443.4458423480. The cubic root of 9888998921 is about 2146.4335261633.

The spelling of 9888998921 in words is "nine billion, eight hundred eighty-eight million, nine hundred ninety-eight thousand, nine hundred twenty-one".