1818221 has 2 divisors, whose sum is σ = 1818222. Its totient is φ = 1818220.

The previous prime is 1818209. The next prime is 1818233. The reversal of 1818221 is 1228181.

It is a happy number.

It is a balanced prime because it is at equal distance from previous prime (1818209) and next prime (1818233).

It can be written as a sum of positive squares in only one way, i.e., 1155625 + 662596 = 1075^2 + 814^2 .

It is an emirp because it is prime and its reverse (1228181) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1818221 - 2¹⁰ = 1817197 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1818241) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 909110 + 909111.

It is an arithmetic number, because the mean of its divisors is an integer number (909111).

2^1818221 is an apocalyptic number.

It is an amenable number.

1818221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1818221 is an equidigital number, since it uses as much as digits as its factorization.

1818221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 256, while the sum is 23.

The square root of 1818221 is about 1348.4142538552. The cubic root of 1818221 is about 122.0531211827.

The spelling of 1818221 in words is "one million, eight hundred eighteen thousand, two hundred twenty-one".