1821121 has 2 divisors, whose sum is σ = 1821122. Its totient is φ = 1821120.

The previous prime is 1821107. The next prime is 1821137. The reversal of 1821121 is 1211281.

It is an a-pointer prime, because the next prime (1821137) can be obtained adding 1821121 to its sum of digits (16).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1718721 + 102400 = 1311^2 + 320^2 .

It is an emirp because it is prime and its reverse (1211281) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1821121 - 2¹⁹ = 1296833 is a prime.

It is an Ulam number.

1821121 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 1821095 and 1821104.

It is not a weakly prime, because it can be changed into another prime (1821101) 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, 910560 + 910561.

It is an arithmetic number, because the mean of its divisors is an integer number (910561).

2^1821121 is an apocalyptic number.

It is an amenable number.

1821121 is a deficient number, since it is larger than the sum of its proper divisors (1).

1821121 is an equidigital number, since it uses as much as digits as its factorization.

1821121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 32, while the sum is 16.

The square root of 1821121 is about 1349.4891626093. The cubic root of 1821121 is about 122.1179768917.

The spelling of 1821121 in words is "one million, eight hundred twenty-one thousand, one hundred twenty-one".