813221 has 2 divisors, whose sum is σ = 813222. Its totient is φ = 813220.

The previous prime is 813217. The next prime is 813227. The reversal of 813221 is 122318.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 664225 + 148996 = 815^2 + 386^2 .

It is a cyclic number.

It is not a de Polignac number, because 813221 - 2² = 813217 is a prime.

It is a super-2 number, since 2×813221² = 1322656789682, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 813221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (813227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 406610 + 406611.

It is an arithmetic number, because the mean of its divisors is an integer number (406611).

2⁸¹³²²¹ is an apocalyptic number.

It is an amenable number.

813221 is a deficient number, since it is larger than the sum of its proper divisors (1).

813221 is an equidigital number, since it uses as much as digits as its factorization.

813221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 96, while the sum is 17.

The square root of 813221 is about 901.7876690219. The cubic root of 813221 is about 93.3403722016.

Adding to 813221 its reverse (122318), we get a palindrome (935539).

The spelling of 813221 in words is "eight hundred thirteen thousand, two hundred twenty-one".