811221 has 4 divisors (see below), whose sum is σ = 1081632.
Its totient is φ = 540812.
The previous prime is 811207. The next prime is 811231. The reversal of 811221 is 122118.
It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.
It is a cyclic number.
It is not a de Polignac number, because 811221 - 26 = 811157 is a prime.
It is a D-number.
811221 is a lucky number.
It is a self number, because there is not a number n which added to its sum of digits gives 811221.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (811231) by changing a digit.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 135201 + ... + 135206.
It is an arithmetic number, because the mean of its divisors is an integer number (270408).
2811221 is an apocalyptic number.
It is an amenable number.
811221 is a deficient number, since it is larger than the sum of its proper divisors (270411).
811221 is a wasteful number, since it uses less digits than its factorization.
811221 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 270410.
The product of its digits is 32, while the sum is 15.
The square root of 811221 is about 900.6780778946.
The cubic root of 811221 is about 93.2637903163.
Adding to 811221 its reverse (122118), we get a palindrome (933339).
The spelling of 811221 in words is "eight hundred eleven thousand, two hundred twenty-one".