1311211021 has 4 divisors (see below), whose sum is σ = 1319062752. Its totient is φ = 1303359292.

The previous prime is 1311211019. The next prime is 1311211049. The reversal of 1311211021 is 1201121131.

It is a happy number.

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.

It is a cyclic number.

It is not a de Polignac number, because 1311211021 - 2¹ = 1311211019 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1311210992 and 1311211010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1311211051) 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, 3925615 + ... + 3925948.

It is an arithmetic number, because the mean of its divisors is an integer number (329765688).

Almost surely, 2^1311211021 is an apocalyptic number.

It is an amenable number.

1311211021 is a deficient number, since it is larger than the sum of its proper divisors (7851731).

1311211021 is an equidigital number, since it uses as much as digits as its factorization.

1311211021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7851730.

The product of its (nonzero) digits is 12, while the sum is 13.

The square root of 1311211021 is about 36210.6478953360. The cubic root of 1311211021 is about 1094.5212480074.

Adding to 1311211021 its reverse (1201121131), we get a palindrome (2512332152).

The spelling of 1311211021 in words is "one billion, three hundred eleven million, two hundred eleven thousand, twenty-one".