1812221 has 4 divisors (see below), whose sum is σ = 1818432. Its totient is φ = 1806012.

The previous prime is 1812199. The next prime is 1812227. The reversal of 1812221 is 1222181.

It is a happy number.

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 1812221 - 2⁶ = 1812157 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1812221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1812227) 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, 2645 + ... + 3258.

It is an arithmetic number, because the mean of its divisors is an integer number (454608).

2^1812221 is an apocalyptic number.

It is an amenable number.

1812221 is a deficient number, since it is larger than the sum of its proper divisors (6211).

1812221 is an equidigital number, since it uses as much as digits as its factorization.

1812221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6210.

The product of its digits is 64, while the sum is 17.

The square root of 1812221 is about 1346.1875797971. The cubic root of 1812221 is about 121.9187176933.

The spelling of 1812221 in words is "one million, eight hundred twelve thousand, two hundred twenty-one".