9847991 has 2 divisors, whose sum is σ = 9847992. Its totient is φ = 9847990.

The previous prime is 9847969. The next prime is 9847993. The reversal of 9847991 is 1997489.

9847991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 9847991 - 2⁶ = 9847927 is a prime.

Together with 9847993, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9847993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4923995 + 4923996.

It is an arithmetic number, because the mean of its divisors is an integer number (4923996).

Almost surely, 2^9847991 is an apocalyptic number.

9847991 is a deficient number, since it is larger than the sum of its proper divisors (1).

9847991 is an equidigital number, since it uses as much as digits as its factorization.

9847991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 163296, while the sum is 47.

The square root of 9847991 is about 3138.1508886604. The cubic root of 9847991 is about 214.3462456085.

The spelling of 9847991 in words is "nine million, eight hundred forty-seven thousand, nine hundred ninety-one".