812221 has 2 divisors, whose sum is σ = 812222. Its totient is φ = 812220.

The previous prime is 812213. The next prime is 812233. The reversal of 812221 is 122218.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 784996 + 27225 = 886^2 + 165^2 .

It is a cyclic number.

It is not a de Polignac number, because 812221 - 2³ = 812213 is a prime.

It is an Ulam number.

It is a junction number, because it is equal to n+sod(n) for n = 812195 and 812204.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (812281) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 406110 + 406111.

It is an arithmetic number, because the mean of its divisors is an integer number (406111).

2⁸¹²²²¹ is an apocalyptic number.

It is an amenable number.

812221 is a deficient number, since it is larger than the sum of its proper divisors (1).

812221 is an equidigital number, since it uses as much as digits as its factorization.

812221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 64, while the sum is 16.

The square root of 812221 is about 901.2330442233. The cubic root of 812221 is about 93.3020969734.

Adding to 812221 its reverse (122218), we get a palindrome (934439).

The spelling of 812221 in words is "eight hundred twelve thousand, two hundred twenty-one".