1311021221243 has 4 divisors (see below), whose sum is σ = 1311023532168. Its totient is φ = 1311018910320.

The previous prime is 1311021221207. The next prime is 1311021221303. The reversal of 1311021221243 is 3421221201131.

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 is a cyclic number.

It is not a de Polignac number, because 1311021221243 - 2¹⁶ = 1311021155707 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1311021221143) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 345008 + ... + 1655618.

It is an arithmetic number, because the mean of its divisors is an integer number (327755883042).

Almost surely, 2^{1311021221243} is an apocalyptic number.

1311021221243 is a deficient number, since it is larger than the sum of its proper divisors (2310925).

1311021221243 is a wasteful number, since it uses less digits than its factorization.

1311021221243 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2310924.

The product of its (nonzero) digits is 576, while the sum is 23.

Adding to 1311021221243 its reverse (3421221201131), we get a palindrome (4732242422374).

The spelling of 1311021221243 in words is "one trillion, three hundred eleven billion, twenty-one million, two hundred twenty-one thousand, two hundred forty-three".