6471991 has 4 divisors (see below), whose sum is σ = 6544800. Its totient is φ = 6399184.

The previous prime is 6471977. The next prime is 6472007. The reversal of 6471991 is 1991746.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 6471991 - 2¹¹ = 6469943 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 6471991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6471391) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36271 + ... + 36448.

It is an arithmetic number, because the mean of its divisors is an integer number (1636200).

Almost surely, 2^6471991 is an apocalyptic number.

6471991 is a deficient number, since it is larger than the sum of its proper divisors (72809).

6471991 is an equidigital number, since it uses as much as digits as its factorization.

6471991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72808.

The product of its digits is 13608, while the sum is 37.

The square root of 6471991 is about 2544.0108097255. The cubic root of 6471991 is about 186.3571105894.

The spelling of 6471991 in words is "six million, four hundred seventy-one thousand, nine hundred ninety-one".