1221221321 has 4 divisors (see below), whose sum is σ = 1227420612. Its totient is φ = 1215022032.

The previous prime is 1221221279. The next prime is 1221221327. The reversal of 1221221321 is 1231221221.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1231221221 = 601 ⋅2048621.

It can be written as a sum of positive squares in 2 ways, for example, as 1204090000 + 17131321 = 34700^2 + 4139^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221221321 - 2²⁶ = 1154112457 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1221221321.

It is not an unprimeable number, because it can be changed into a prime (1221221327) 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, 3099350 + ... + 3099743.

It is an arithmetic number, because the mean of its divisors is an integer number (306855153).

Almost surely, 2^1221221321 is an apocalyptic number.

It is an amenable number.

1221221321 is a deficient number, since it is larger than the sum of its proper divisors (6199291).

1221221321 is an equidigital number, since it uses as much as digits as its factorization.

1221221321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6199290.

The product of its digits is 96, while the sum is 17.

The square root of 1221221321 is about 34945.9771790688. The cubic root of 1221221321 is about 1068.8861734723.

Adding to 1221221321 its reverse (1231221221), we get a palindrome (2452442542).

It can be divided in two parts, 12212 and 21321, that added together give a palindrome (33533).

The spelling of 1221221321 in words is "one billion, two hundred twenty-one million, two hundred twenty-one thousand, three hundred twenty-one".