1321220321 has 4 divisors (see below), whose sum is σ = 1321422000. Its totient is φ = 1321018644.

The previous prime is 1321220317. The next prime is 1321220359. The reversal of 1321220321 is 1230221231.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1230221231 = 997 ⋅1233923.

It is a cyclic number.

It is not a de Polignac number, because 1321220321 - 2² = 1321220317 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 1321220321.

It is not an unprimeable number, because it can be changed into a prime (1321220821) 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, 90671 + ... + 104228.

It is an arithmetic number, because the mean of its divisors is an integer number (330355500).

Almost surely, 2^1321220321 is an apocalyptic number.

It is an amenable number.

1321220321 is a deficient number, since it is larger than the sum of its proper divisors (201679).

1321220321 is an equidigital number, since it uses as much as digits as its factorization.

1321220321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 201678.

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

The square root of 1321220321 is about 36348.5944845189. The cubic root of 1321220321 is about 1097.2992480158.

Adding to 1321220321 its reverse (1230221231), we get a palindrome (2551441552).

It can be divided in two parts, 13212 and 20321, that added together give a palindrome (33533).

The spelling of 1321220321 in words is "one billion, three hundred twenty-one million, two hundred twenty thousand, three hundred twenty-one".