231221031311 has 2 divisors, whose sum is σ = 231221031312. Its totient is φ = 231221031310.

The previous prime is 231221031299. The next prime is 231221031359. The reversal of 231221031311 is 113130122132.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 231221031311 - 2⁶ = 231221031247 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (231221031011) 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 as a sum of consecutive naturals, namely, 115610515655 + 115610515656.

It is an arithmetic number, because the mean of its divisors is an integer number (115610515656).

Almost surely, 2^231221031311 is an apocalyptic number.

231221031311 is a deficient number, since it is larger than the sum of its proper divisors (1).

231221031311 is an equidigital number, since it uses as much as digits as its factorization.

231221031311 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 216, while the sum is 20.

Adding to 231221031311 its reverse (113130122132), we get a palindrome (344351153443).

The spelling of 231221031311 in words is "two hundred thirty-one billion, two hundred twenty-one million, thirty-one thousand, three hundred eleven".