6487991 has 2 divisors, whose sum is σ = 6487992. Its totient is φ = 6487990.

The previous prime is 6487979. The next prime is 6487993. The reversal of 6487991 is 1997846.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6487991 is a prime.

It is a Sophie Germain prime.

Together with 6487993, 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 (6487993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3243995 + 3243996.

It is an arithmetic number, because the mean of its divisors is an integer number (3243996).

Almost surely, 2^6487991 is an apocalyptic number.

6487991 is a deficient number, since it is larger than the sum of its proper divisors (1).

6487991 is an equidigital number, since it uses as much as digits as its factorization.

6487991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 108864, while the sum is 44.

The square root of 6487991 is about 2547.1535093119. The cubic root of 6487991 is about 186.5105543553.

The spelling of 6487991 in words is "six million, four hundred eighty-seven thousand, nine hundred ninety-one".