6831991 has 2 divisors, whose sum is σ = 6831992. Its totient is φ = 6831990.

The previous prime is 6831971. The next prime is 6832003. The reversal of 6831991 is 1991386.

6831991 is digitally balanced in base 3, 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 6831991 - 2⁷ = 6831863 is a prime.

It is a super-2 number, since 2×6831991² = 93352202048162, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 6831991.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6831911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3415995 + 3415996.

It is an arithmetic number, because the mean of its divisors is an integer number (3415996).

Almost surely, 2^6831991 is an apocalyptic number.

6831991 is a deficient number, since it is larger than the sum of its proper divisors (1).

6831991 is an equidigital number, since it uses as much as digits as its factorization.

6831991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11664, while the sum is 37.

The square root of 6831991 is about 2613.8077588071. The cubic root of 6831991 is about 189.7502813547.

The spelling of 6831991 in words is "six million, eight hundred thirty-one thousand, nine hundred ninety-one".