6847991 has 4 divisors (see below), whose sum is σ = 7250832. Its totient is φ = 6445152.

The previous prime is 6847979. The next prime is 6848027. The reversal of 6847991 is 1997486.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1997486 = 2 ⋅998743.

It is a cyclic number.

It is not a de Polignac number, because 6847991 - 2¹⁰ = 6846967 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6847091) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 201395 + ... + 201428.

It is an arithmetic number, because the mean of its divisors is an integer number (1812708).

Almost surely, 2^6847991 is an apocalyptic number.

6847991 is a deficient number, since it is larger than the sum of its proper divisors (402841).

6847991 is a wasteful number, since it uses less digits than its factorization.

6847991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 402840.

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

The square root of 6847991 is about 2616.8666377941. The cubic root of 6847991 is about 189.8982927494.

The spelling of 6847991 in words is "six million, eight hundred forty-seven thousand, nine hundred ninety-one".