6291991 has 2 divisors, whose sum is σ = 6291992. Its totient is φ = 6291990.

The previous prime is 6291973. The next prime is 6292007. The reversal of 6291991 is 1991926.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 6291991 - 2⁵ = 6291959 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 6291991.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6291911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3145995 + 3145996.

It is an arithmetic number, because the mean of its divisors is an integer number (3145996).

Almost surely, 2^6291991 is an apocalyptic number.

6291991 is a deficient number, since it is larger than the sum of its proper divisors (1).

6291991 is an equidigital number, since it uses as much as digits as its factorization.

6291991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8748, while the sum is 37.

The square root of 6291991 is about 2508.3841412351. The cubic root of 6291991 is about 184.6131776223.

The spelling of 6291991 in words is "six million, two hundred ninety-one thousand, nine hundred ninety-one".