9891997 has 2 divisors, whose sum is σ = 9891998. Its totient is φ = 9891996.

The previous prime is 9891991. The next prime is 9892009. The reversal of 9891997 is 7991989.

9891997 is digitally balanced in base 3, 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., 6832996 + 3059001 = 2614^2 + 1749^2 .

9891997 is a truncatable prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-9891997 is a prime.

It is a super-3 number, since 3×9891997³ (a number of 22 digits) contains 333 as substring.

It is an Ulam number.

9891997 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9891991) 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, 4945998 + 4945999.

It is an arithmetic number, because the mean of its divisors is an integer number (4945999).

Almost surely, 2^9891997 is an apocalyptic number.

It is an amenable number.

9891997 is a deficient number, since it is larger than the sum of its proper divisors (1).

9891997 is an equidigital number, since it uses as much as digits as its factorization.

9891997 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 367416, while the sum is 52.

The square root of 9891997 is about 3145.1545272053. The cubic root of 9891997 is about 214.6650417921.

The spelling of 9891997 in words is "nine million, eight hundred ninety-one thousand, nine hundred ninety-seven".