231312311221 has 2 divisors, whose sum is σ = 231312311222. Its totient is φ = 231312311220.

The previous prime is 231312311201. The next prime is 231312311257. The reversal of 231312311221 is 122113213132.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 152791864996 + 78520446225 = 390886^2 + 280215^2 .

It is a cyclic number.

It is not a de Polignac number, because 231312311221 - 2⁵ = 231312311189 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 231312311192 and 231312311201.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (231312311201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 115656155610 + 115656155611.

It is an arithmetic number, because the mean of its divisors is an integer number (115656155611).

Almost surely, 2^231312311221 is an apocalyptic number.

It is an amenable number.

231312311221 is a deficient number, since it is larger than the sum of its proper divisors (1).

231312311221 is an equidigital number, since it uses as much as digits as its factorization.

231312311221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 432, while the sum is 22.

Adding to 231312311221 its reverse (122113213132), we get a palindrome (353425524353).

The spelling of 231312311221 in words is "two hundred thirty-one billion, three hundred twelve million, three hundred eleven thousand, two hundred twenty-one".