12220721 has 2 divisors, whose sum is σ = 12220722. Its totient is φ = 12220720.

The previous prime is 12220717. The next prime is 12220757. The reversal of 12220721 is 12702221.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10368400 + 1852321 = 3220^2 + 1361^2 .

It is a cyclic number.

It is not a de Polignac number, because 12220721 - 2² = 12220717 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 12220721.

It is not a weakly prime, because it can be changed into another prime (12220771) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6110360 + 6110361.

It is an arithmetic number, because the mean of its divisors is an integer number (6110361).

Almost surely, 2^12220721 is an apocalyptic number.

It is an amenable number.

12220721 is a deficient number, since it is larger than the sum of its proper divisors (1).

12220721 is an equidigital number, since it uses as much as digits as its factorization.

12220721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 112, while the sum is 17.

The square root of 12220721 is about 3495.8147834232. The cubic root of 12220721 is about 230.3380096316.

Adding to 12220721 its reverse (12702221), we get a palindrome (24922942).

The spelling of 12220721 in words is "twelve million, two hundred twenty thousand, seven hundred twenty-one".