1211320321 has 4 divisors (see below), whose sum is σ = 1211402500. Its totient is φ = 1211238144.

The previous prime is 1211320301. The next prime is 1211320333. The reversal of 1211320321 is 1230231121.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 903844096 + 307476225 = 30064^2 + 17535^2 .

It is a cyclic number.

It is not a de Polignac number, because 1211320321 - 2¹⁷ = 1211189249 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1211320295 and 1211320304.

It is not an unprimeable number, because it can be changed into a prime (1211320301) 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, 12216 + ... + 50713.

It is an arithmetic number, because the mean of its divisors is an integer number (302850625).

Almost surely, 2^1211320321 is an apocalyptic number.

It is an amenable number.

1211320321 is a deficient number, since it is larger than the sum of its proper divisors (82179).

1211320321 is an equidigital number, since it uses as much as digits as its factorization.

1211320321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82178.

The product of its (nonzero) digits is 72, while the sum is 16.

The square root of 1211320321 is about 34804.0273675332. The cubic root of 1211320321 is about 1065.9896818308.

Adding to 1211320321 its reverse (1230231121), we get a palindrome (2441551442).

It can be divided in two parts, 1211 and 320321, that multiplied together give a triangular number (387908731 = T₂₇₈₅₃).

The spelling of 1211320321 in words is "one billion, two hundred eleven million, three hundred twenty thousand, three hundred twenty-one".