819 has 12 divisors (see below), whose sum is σ = 1456. Its totient is φ = 432.

The previous prime is 811. The next prime is 821. The reversal of 819 is 918.

Subtracting from 819 its product of digits (72), we obtain a palindrome (747).

Subtracting 819 from its reverse (918), we obtain a palindrome (99).

It can be divided in two parts, 81 and 9, that multiplied together give a 6-th power (729 = 3^{6}).

819 = 1^{2} + 2^{2} + ... + 13^{2}.

819 is nontrivially palindromic in base 2, base 4, base 6 and base 16.

It is not a de Polignac number, because 819 - 2^{3} = 811 is a prime.

It is a super-2 number, since 2×819^{2} = 1341522, which contains 22 as substring.

It is a D-number.

819 is an undulating number in base 4.

819 is a lucky number.

819 is a nontrivial repdigit in base 16.

It is a plaindrome in base 5, base 15 and base 16.

It is a nialpdrome in base 9 and base 16.

It is a zygodrome in base 2 and base 16.

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

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 57 + ... + 69.

2^{819} is an apocalyptic number.

819 is a deficient number, since it is larger than the sum of its proper divisors (637).

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

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

The sum of its prime factors is 26 (or 23 counting only the distinct ones).

The product of its digits is 72, while the sum is 18.

The square root of 819 is about 28.6181760425. The cubic root of 819 is about 9.3560952374.

The spelling of 819 in words is "eight hundred nineteen", and thus it is an aban number and an oban number.

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