31320231221 has 2 divisors, whose sum is σ = 31320231222. Its totient is φ = 31320231220.

The previous prime is 31320231203. The next prime is 31320231251. The reversal of 31320231221 is 12213202313.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 23566548196 + 7753683025 = 153514^2 + 88055^2 .

It is a cyclic number.

It is not a de Polignac number, because 31320231221 - 2¹⁸ = 31319969077 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 31320231193 and 31320231202.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31320231251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15660115610 + 15660115611.

It is an arithmetic number, because the mean of its divisors is an integer number (15660115611).

Almost surely, 2^31320231221 is an apocalyptic number.

It is an amenable number.

31320231221 is a deficient number, since it is larger than the sum of its proper divisors (1).

31320231221 is an equidigital number, since it uses as much as digits as its factorization.

31320231221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 432, while the sum is 20.

Adding to 31320231221 its reverse (12213202313), we get a palindrome (43533433534).

The spelling of 31320231221 in words is "thirty-one billion, three hundred twenty million, two hundred thirty-one thousand, two hundred twenty-one".