810 can be written using four 4's:
See also 113
810 has 20
divisors (see below), whose sum is σ = 2178
Its totient is φ = 216
The previous prime is 809. The next prime is 811. The reversal of 810 is 18.
810 is nontrivially palindromic in base 13.
810 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.
It is an interprime number because it is at equal distance from previous prime (809) and next prime (811).
It can be written as a sum of positive squares in only one way, i.e., 729 + 81 = 27^2 + 9^2
It is a super-2 number, since 2×8102 = 1312200, which contains 22 as substring.
It is a Harshad number since it is a multiple of its sum of digits (9).
It is an alternating number because its digits alternate between even and odd.
810 is an undulating number in base 13.
It is a Curzon number.
It is a plaindrome in base 7 and base 11.
It is a nialpdrome in base 9 and base 10.
It is a zygodrome in base 9.
It is a junction number, because it is equal to n+sod(n) for n = 792 and 801.
It is not an unprimeable number, because it can be changed into a prime (811) by changing a digit.
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 9 ways as a sum of consecutive naturals, for example, 160 + ... + 164.
It is a practical number, because each smaller number is the sum of distinct divisors of 810, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1089).
810 is an abundant number, since it is smaller than the sum of its proper divisors (1368).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
810 is a wasteful number, since it uses less digits than its factorization.
810 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 19 (or 10 counting only the distinct ones).
The product of its (nonzero) digits is 8, while the sum is 9.
The square root of 810 is about 28.4604989415.
The cubic root of 810 is about 9.3216975179.
Adding to 810 its reverse (18), we get a palindrome (828).
810 divided by its reverse (18) gives a triangular number (45 = T9).
The spelling of 810 in words is "eight hundred ten", and thus it is an aban number and an oban number.