31323320221 has 2 divisors, whose sum is σ = 31323320222. Its totient is φ = 31323320220.

The previous prime is 31323320159. The next prime is 31323320243. The reversal of 31323320221 is 12202332313.

It is an a-pointer prime, because the next prime (31323320243) can be obtained adding 31323320221 to its sum of digits (22).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20922176025 + 10401144196 = 144645^2 + 101986^2 .

It is a cyclic number.

It is not a de Polignac number, because 31323320221 - 2¹⁵ = 31323287453 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 31323320192 and 31323320201.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31323320321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15661660110 + 15661660111.

It is an arithmetic number, because the mean of its divisors is an integer number (15661660111).

Almost surely, 2^31323320221 is an apocalyptic number.

It is an amenable number.

31323320221 is a deficient number, since it is larger than the sum of its proper divisors (1).

31323320221 is an equidigital number, since it uses as much as digits as its factorization.

31323320221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1296, while the sum is 22.

Adding to 31323320221 its reverse (12202332313), we get a palindrome (43525652534).

The spelling of 31323320221 in words is "thirty-one billion, three hundred twenty-three million, three hundred twenty thousand, two hundred twenty-one".