6887991 has 16 divisors (see below), whose sum is σ = 10234368. Its totient is φ = 4084800.

The previous prime is 6887953. The next prime is 6888019. The reversal of 6887991 is 1997886.

It is a happy number.

It is not a de Polignac number, because 6887991 - 2⁶ = 6887927 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 6887991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6887791) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 670 + ... + 3771.

It is an arithmetic number, because the mean of its divisors is an integer number (639648).

Almost surely, 2^6887991 is an apocalyptic number.

6887991 is a deficient number, since it is larger than the sum of its proper divisors (3346377).

6887991 is a wasteful number, since it uses less digits than its factorization.

6887991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4502.

The product of its digits is 217728, while the sum is 48.

The square root of 6887991 is about 2624.4982377590. The cubic root of 6887991 is about 190.2673153290.

The spelling of 6887991 in words is "six million, eight hundred eighty-seven thousand, nine hundred ninety-one".