31320251621221 has 2 divisors, whose sum is σ = 31320251621222. Its totient is φ = 31320251621220.

The previous prime is 31320251621189. The next prime is 31320251621273. The reversal of 31320251621221 is 12212615202313.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 31237200450625 + 83051170596 = 5589025^2 + 288186^2 .

It is an emirp because it is prime and its reverse (12212615202313) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31320251621221 - 2⁵ = 31320251621189 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31320251621921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15660125810610 + 15660125810611.

It is an arithmetic number, because the mean of its divisors is an integer number (15660125810611).

Almost surely, 2^{31320251621221} is an apocalyptic number.

It is an amenable number.

31320251621221 is a deficient number, since it is larger than the sum of its proper divisors (1).

31320251621221 is an equidigital number, since it uses as much as digits as its factorization.

31320251621221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8640, while the sum is 31.

Adding to 31320251621221 its reverse (12212615202313), we get a palindrome (43532866823534).

The spelling of 31320251621221 in words is "thirty-one trillion, three hundred twenty billion, two hundred fifty-one million, six hundred twenty-one thousand, two hundred twenty-one".