1311222221 has 4 divisors (see below), whose sum is σ = 1353519744. Its totient is φ = 1268924700.

The previous prime is 1311222197. The next prime is 1311222233. The reversal of 1311222221 is 1222221131.

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: 1222221131 = 14071 ⋅86861.

It is a cyclic number.

It is not a de Polignac number, because 1311222221 - 2²⁶ = 1244113357 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 1311222221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1311222251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21148715 + ... + 21148776.

It is an arithmetic number, because the mean of its divisors is an integer number (338379936).

Almost surely, 2^1311222221 is an apocalyptic number.

It is an amenable number.

1311222221 is a deficient number, since it is larger than the sum of its proper divisors (42297523).

1311222221 is an equidigital number, since it uses as much as digits as its factorization.

1311222221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42297522.

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

The square root of 1311222221 is about 36210.8025456493. The cubic root of 1311222221 is about 1094.5243643640.

Adding to 1311222221 its reverse (1222221131), we get a palindrome (2533443352).

The spelling of 1311222221 in words is "one billion, three hundred eleven million, two hundred twenty-two thousand, two hundred twenty-one".