9988921 has 2 divisors, whose sum is σ = 9988922. Its totient is φ = 9988920.

The previous prime is 9988907. The next prime is 9988939. The reversal of 9988921 is 1298899.

It is a happy number.

9988921 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., 8042896 + 1946025 = 2836^2 + 1395^2 .

It is a cyclic number.

It is not a de Polignac number, because 9988921 - 2⁷ = 9988793 is a prime.

It is not a weakly prime, because it can be changed into another prime (9988981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4994460 + 4994461.

It is an arithmetic number, because the mean of its divisors is an integer number (4994461).

Almost surely, 2^9988921 is an apocalyptic number.

It is an amenable number.

9988921 is a deficient number, since it is larger than the sum of its proper divisors (1).

9988921 is an equidigital number, since it uses as much as digits as its factorization.

9988921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 93312, while the sum is 46.

The square root of 9988921 is about 3160.5254310004. The cubic root of 9988921 is about 215.3638763293.

The spelling of 9988921 in words is "nine million, nine hundred eighty-eight thousand, nine hundred twenty-one".