2211821 has 2 divisors, whose sum is σ = 2211822. Its totient is φ = 2211820.

The previous prime is 2211817. The next prime is 2211883. The reversal of 2211821 is 1281122.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1990921 + 220900 = 1411^2 + 470^2 .

It is a cyclic number.

It is not a de Polignac number, because 2211821 - 2² = 2211817 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 2211821.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2216821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1105910 + 1105911.

It is an arithmetic number, because the mean of its divisors is an integer number (1105911).

2^2211821 is an apocalyptic number.

It is an amenable number.

2211821 is a deficient number, since it is larger than the sum of its proper divisors (1).

2211821 is an equidigital number, since it uses as much as digits as its factorization.

2211821 is an odious number, because the sum of its binary digits is odd.

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

The square root of 2211821 is about 1487.2192171970. The cubic root of 2211821 is about 130.2916725201.

Adding to 2211821 its reverse (1281122), we get a palindrome (3492943).

It can be divided in two parts, 22 and 11821, that multiplied together give a palindrome (260062).

The spelling of 2211821 in words is "two million, two hundred eleven thousand, eight hundred twenty-one".