1221320213 has 4 divisors (see below), whose sum is σ = 1221801900. Its totient is φ = 1220838528.

The previous prime is 1221320197. The next prime is 1221320227. The reversal of 1221320213 is 3120231221.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1101045124 + 120275089 = 33182^2 + 10967^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221320213 - 2⁴ = 1221320197 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1221320191 and 1221320200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221320293) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 237020 + ... + 242117.

It is an arithmetic number, because the mean of its divisors is an integer number (305450475).

Almost surely, 2^1221320213 is an apocalyptic number.

It is an amenable number.

1221320213 is a deficient number, since it is larger than the sum of its proper divisors (481687).

1221320213 is an equidigital number, since it uses as much as digits as its factorization.

1221320213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 481686.

The product of its (nonzero) digits is 144, while the sum is 17.

The square root of 1221320213 is about 34947.3920772352. The cubic root of 1221320213 is about 1068.9150247642.

Adding to 1221320213 its reverse (3120231221), we get a palindrome (4341551434).

The spelling of 1221320213 in words is "one billion, two hundred twenty-one million, three hundred twenty thousand, two hundred thirteen".