31021121221 has 2 divisors, whose sum is σ = 31021121222. Its totient is φ = 31021121220.

The previous prime is 31021121213. The next prime is 31021121309. The reversal of 31021121221 is 12212112013.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 30439780900 + 581340321 = 174470^2 + 24111^2 .

It is an emirp because it is prime and its reverse (12212112013) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31021121221 - 2³ = 31021121213 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 31021121195 and 31021121204.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31021121321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15510560610 + 15510560611.

It is an arithmetic number, because the mean of its divisors is an integer number (15510560611).

Almost surely, 2^31021121221 is an apocalyptic number.

It is an amenable number.

31021121221 is a deficient number, since it is larger than the sum of its proper divisors (1).

31021121221 is an equidigital number, since it uses as much as digits as its factorization.

31021121221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 48, while the sum is 16.

Adding to 31021121221 its reverse (12212112013), we get a palindrome (43233233234).

The spelling of 31021121221 in words is "thirty-one billion, twenty-one million, one hundred twenty-one thousand, two hundred twenty-one".