8491591 has 2 divisors, whose sum is σ = 8491592. Its totient is φ = 8491590.

The previous prime is 8491589. The next prime is 8491621. The reversal of 8491591 is 1951948.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 8491591 - 2¹ = 8491589 is a prime.

It is a super-2 number, since 2×8491591² = 144214235422562, which contains 22 as substring.

Together with 8491589, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 8491591.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8491541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4245795 + 4245796.

It is an arithmetic number, because the mean of its divisors is an integer number (4245796).

Almost surely, 2^8491591 is an apocalyptic number.

8491591 is a deficient number, since it is larger than the sum of its proper divisors (1).

8491591 is an equidigital number, since it uses as much as digits as its factorization.

8491591 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12960, while the sum is 37.

The square root of 8491591 is about 2914.0334589706. The cubic root of 8491591 is about 204.0154336010.

The spelling of 8491591 in words is "eight million, four hundred ninety-one thousand, five hundred ninety-one".