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6816 = 25371

6816 has 24 divisors (see below), whose sum is σ = 18144. Its totient is φ = 2240.

The previous prime is 6803. The next prime is 6823. The reversal of 6816 is 6186.

Subtracting from 6816 its reverse (6186), we obtain a triangular number (630 = T35).

It is a tau number, because it is divible by the number of its divisors (24).

It is a Smith number, since the sum of its digits (21) coincides with the sum of the digits of its prime factors.

It is a nude number because it is divisible by every one of its digits.

It is a plaindrome in base 14.

It is a junction number, because it is equal to n+sod(n) for n = 6792 and 6801.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 6816.

It is an unprimeable number.

6816 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 61 + ... + 131.

It is an arithmetic number, because the mean of its divisors is an integer number (756).

26816 is an apocalyptic number.

6816 is the 48-th octagonal number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (9072).

6816 is an abundant number, since it is smaller than the sum of its proper divisors (11328).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

6816 is a wasteful number, since it uses less digits than its factorization.

6816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84 (or 76 counting only the distinct ones).

The product of its digits is 288, while the sum is 21.

The square root of 6816 is about 82.5590697622. The cubic root of 6816 is about 18.9602122143.

The spelling of 6816 in words is "six thousand, eight hundred sixteen".

Divisors: 1 2 3 4 6 8 12 16 24 32 48 71 96 142 213 284 426 568 852 1136 1704 2272 3408 6816