1231311121 has 2 divisors, whose sum is σ = 1231311122. Its totient is φ = 1231311120.

The previous prime is 1231311119. The next prime is 1231311127. The reversal of 1231311121 is 1211131321.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1084780096 + 146531025 = 32936^2 + 12105^2 .

It is a cyclic number.

It is not a de Polignac number, because 1231311121 - 2¹ = 1231311119 is a prime.

It is a super-2 number, since 2×1231311121² = 3032254153396553282, which contains 22 as substring.

Together with 1231311119, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 1231311095 and 1231311104.

It is not a weakly prime, because it can be changed into another prime (1231311127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 615655560 + 615655561.

It is an arithmetic number, because the mean of its divisors is an integer number (615655561).

Almost surely, 2^1231311121 is an apocalyptic number.

It is an amenable number.

1231311121 is a deficient number, since it is larger than the sum of its proper divisors (1).

1231311121 is an equidigital number, since it uses as much as digits as its factorization.

1231311121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 36, while the sum is 16.

The square root of 1231311121 is about 35090.0430464256. The cubic root of 1231311121 is about 1071.8218361673.

Adding to 1231311121 its reverse (1211131321), we get a palindrome (2442442442).

The spelling of 1231311121 in words is "one billion, two hundred thirty-one million, three hundred eleven thousand, one hundred twenty-one".