9891121 has 2 divisors, whose sum is σ = 9891122. Its totient is φ = 9891120.

The previous prime is 9891097. The next prime is 9891131. The reversal of 9891121 is 1211989.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 8767521 + 1123600 = 2961^2 + 1060^2 .

It is a cyclic number.

It is not a de Polignac number, because 9891121 - 2⁹ = 9890609 is a prime.

It is not a weakly prime, because it can be changed into another prime (9891131) 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, 4945560 + 4945561.

It is an arithmetic number, because the mean of its divisors is an integer number (4945561).

Almost surely, 2^9891121 is an apocalyptic number.

It is an amenable number.

9891121 is a deficient number, since it is larger than the sum of its proper divisors (1).

9891121 is an equidigital number, since it uses as much as digits as its factorization.

9891121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1296, while the sum is 31.

The square root of 9891121 is about 3145.0152622841. The cubic root of 9891121 is about 214.6587049480.

It can be divided in two parts, 98 and 91121, that added together give a palindrome (91219).

The spelling of 9891121 in words is "nine million, eight hundred ninety-one thousand, one hundred twenty-one".