31331221321 has 2 divisors, whose sum is σ = 31331221322. Its totient is φ = 31331221320.

The previous prime is 31331221303. The next prime is 31331221403. The reversal of 31331221321 is 12312213313.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 26398125625 + 4933095696 = 162475^2 + 70236^2 .

It is a cyclic number.

It is not a de Polignac number, because 31331221321 - 2¹¹ = 31331219273 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 31331221292 and 31331221301.

It is not a weakly prime, because it can be changed into another prime (31331221301) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15665610660 + 15665610661.

It is an arithmetic number, because the mean of its divisors is an integer number (15665610661).

Almost surely, 2^31331221321 is an apocalyptic number.

It is an amenable number.

31331221321 is a deficient number, since it is larger than the sum of its proper divisors (1).

31331221321 is an equidigital number, since it uses as much as digits as its factorization.

31331221321 is an evil number, because the sum of its binary digits is even.

The product of its digits is 648, while the sum is 22.

Adding to 31331221321 its reverse (12312213313), we get a palindrome (43643434634).

The spelling of 31331221321 in words is "thirty-one billion, three hundred thirty-one million, two hundred twenty-one thousand, three hundred twenty-one".