821812 has 6 divisors (see below), whose sum is σ = 1438178. Its totient is φ = 410904.

The previous prime is 821809. The next prime is 821819. The reversal of 821812 is 218128.

821812 is nontrivially palindromic in base 3.

It can be written as a sum of positive squares in only one way, i.e., 417316 + 404496 = 646^2 + 636^2 .

It is an Ulam number.

It is a plaindrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102723 + ... + 102730.

2⁸²¹⁸¹² is an apocalyptic number.

It is an amenable number.

821812 is a deficient number, since it is larger than the sum of its proper divisors (616366).

821812 is a wasteful number, since it uses less digits than its factorization.

821812 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 205457 (or 205455 counting only the distinct ones).

The product of its digits is 256, while the sum is 22.

The square root of 821812 is about 906.5384713293. The cubic root of 821812 is about 93.6679091764.

The spelling of 821812 in words is "eight hundred twenty-one thousand, eight hundred twelve".