1821191 has 2 divisors, whose sum is σ = 1821192. Its totient is φ = 1821190.

The previous prime is 1821181. The next prime is 1821233. The reversal of 1821191 is 1911281.

It is a weak prime.

It is an emirp because it is prime and its reverse (1911281) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1821191 is a prime.

It is a congruent number.

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, 910595 + 910596.

It is an arithmetic number, because the mean of its divisors is an integer number (910596).

2^1821191 is an apocalyptic number.

1821191 is a deficient number, since it is larger than the sum of its proper divisors (1).

1821191 is an equidigital number, since it uses as much as digits as its factorization.

1821191 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 144, while the sum is 23.

The square root of 1821191 is about 1349.5150981001. The cubic root of 1821191 is about 122.1195415231.

The spelling of 1821191 in words is "one million, eight hundred twenty-one thousand, one hundred ninety-one".