13221220 has 12 divisors (see below), whose sum is σ = 27764604. Its totient is φ = 5288480.

The previous prime is 13221209. The next prime is 13221227. The reversal of 13221220 is 2212231.

It can be written as a sum of positive squares in 2 ways, for example, as 7986276 + 5234944 = 2826^2 + 2288^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 13221220.

It is not an unprimeable number, because it can be changed into a prime (13221227) 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 in 3 ways as a sum of consecutive naturals, for example, 330511 + ... + 330550.

It is an arithmetic number, because the mean of its divisors is an integer number (2313717).

Almost surely, 2^13221220 is an apocalyptic number.

13221220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

13221220 is an abundant number, since it is smaller than the sum of its proper divisors (14543384).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

13221220 is a wasteful number, since it uses less digits than its factorization.

13221220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 661070 (or 661068 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 13.

The square root of 13221220 is about 3636.0995585930. The cubic root of 13221220 is about 236.4597234399.

Adding to 13221220 its reverse (2212231), we get a palindrome (15433451).

The spelling of 13221220 in words is "thirteen million, two hundred twenty-one thousand, two hundred twenty".