9917891 has 2 divisors, whose sum is σ = 9917892. Its totient is φ = 9917890.

The previous prime is 9917881. The next prime is 9917903. The reversal of 9917891 is 1987199.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 9917891 - 2⁶ = 9917827 is a prime.

It is not a weakly prime, because it can be changed into another prime (9917881) 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, 4958945 + 4958946.

It is an arithmetic number, because the mean of its divisors is an integer number (4958946).

Almost surely, 2^9917891 is an apocalyptic number.

9917891 is a deficient number, since it is larger than the sum of its proper divisors (1).

9917891 is an equidigital number, since it uses as much as digits as its factorization.

9917891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 40824, while the sum is 44.

The square root of 9917891 is about 3149.2683277231. The cubic root of 9917891 is about 214.8521861234.

The spelling of 9917891 in words is "nine million, nine hundred seventeen thousand, eight hundred ninety-one".