31311211221 has 12 divisors (see below), whose sum is σ = 45340096620. Its totient is φ = 20822083200.

The previous prime is 31311211171. The next prime is 31311211223. The reversal of 31311211221 is 12211211313.

It can be written as a sum of positive squares in 2 ways, for example, as 16521246225 + 14789964996 = 128535^2 + 121614^2 .

It is not a de Polignac number, because 31311211221 - 2¹³ = 31311203029 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 31311211194 and 31311211203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31311211223) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4334326 + ... + 4341543.

It is an arithmetic number, because the mean of its divisors is an integer number (3778341385).

Almost surely, 2^31311211221 is an apocalyptic number.

It is an amenable number.

31311211221 is a deficient number, since it is larger than the sum of its proper divisors (14028885399).

31311211221 is a wasteful number, since it uses less digits than its factorization.

31311211221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8676276 (or 8676273 counting only the distinct ones).

The product of its digits is 72, while the sum is 18.

Adding to 31311211221 its reverse (12211211313), we get a palindrome (43522422534).

The spelling of 31311211221 in words is "thirty-one billion, three hundred eleven million, two hundred eleven thousand, two hundred twenty-one".