9981689 has 2 divisors, whose sum is σ = 9981690. Its totient is φ = 9981688.

The previous prime is 9981661. The next prime is 9981691. The reversal of 9981689 is 9861899.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 8456464 + 1525225 = 2908^2 + 1235^2 .

It is a cyclic number.

It is not a de Polignac number, because 9981689 - 2¹² = 9977593 is a prime.

Together with 9981691, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (9981889) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4990844 + 4990845.

It is an arithmetic number, because the mean of its divisors is an integer number (4990845).

Almost surely, 2^9981689 is an apocalyptic number.

It is an amenable number.

9981689 is a deficient number, since it is larger than the sum of its proper divisors (1).

9981689 is an equidigital number, since it uses as much as digits as its factorization.

9981689 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 279936, while the sum is 50.

The square root of 9981689 is about 3159.3811102809. The cubic root of 9981689 is about 215.3118891465.

The spelling of 9981689 in words is "nine million, nine hundred eighty-one thousand, six hundred eighty-nine".