6547991 has 4 divisors (see below), whose sum is σ = 6671592. Its totient is φ = 6424392.

The previous prime is 6547979. The next prime is 6548023. The reversal of 6547991 is 1997456.

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 6547991 - 2¹⁸ = 6285847 is a prime.

It is a super-2 number, since 2×6547991² = 85752372272162, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6547291) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 61721 + ... + 61826.

It is an arithmetic number, because the mean of its divisors is an integer number (1667898).

Almost surely, 2^6547991 is an apocalyptic number.

6547991 is a deficient number, since it is larger than the sum of its proper divisors (123601).

6547991 is a wasteful number, since it uses less digits than its factorization.

6547991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 123600.

The product of its digits is 68040, while the sum is 41.

The square root of 6547991 is about 2558.9042576853. The cubic root of 6547991 is about 187.0837319361.

The spelling of 6547991 in words is "six million, five hundred forty-seven thousand, nine hundred ninety-one".