• 816 can be written using four 4's:

816 has 20 divisors (see below), whose sum is σ = 2232. Its totient is φ = 256.

The previous prime is 811. The next prime is 821. The reversal of 816 is 618.

816 = T_{1} + T_{2} + ... +
T_{16}.

816 is nontrivially palindromic in base 14.

816 is a nontrivial binomial coefficient, being equal to C(18, 3).

It is an interprime number because it is at equal distance from previous prime (811) and next prime (821).

It is a nude number because it is divisible by every one of its digits and also a Zuckerman number because it is divisible by the product of its digits.

It is an alternating number because its digits alternate between even and odd.

It is one of the 548 Lynch-Bell numbers.

816 is an undulating number in base 14.

It is a plaindrome in base 7 and base 13.

It is a nialpdrome in base 16.

It is a zygodrome in base 2 and base 7.

It is a junction number, because it is equal to *n*+sod(*n*) for *n* = 795 and 804.

It is an inconsummate number, since it does not exist a number *n* which divided by its sum of digits gives 816.

It is not an unprimeable number, because it can be changed into a prime (811) by changing a digit.

It is the 16-th tetrahedral number.

In principle, a polygon with 816 sides can be constructed with ruler and compass.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 40 + ... + 56.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1116).

816 is an abundant number, since it is smaller than the sum of its proper divisors (1416).

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

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

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

The sum of its prime factors is 28 (or 22 counting only the distinct ones).

The product of its digits is 48, while the sum is 15.

The square root of 816 is about 28.5657137142. The cubic root of 816 is about 9.3446574567.

It can be divided in two parts, 8 and 16, that multiplied together give a 7-th power (128 = 2^{7}).

The spelling of 816 in words is "eight hundred sixteen", and thus it is an aban number and an oban number.

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