31212212321 has 4 divisors (see below), whose sum is σ = 31219978644. Its totient is φ = 31204446000.

The previous prime is 31212212293. The next prime is 31212212357. The reversal of 31212212321 is 12321221213.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 16088131921 + 15124080400 = 126839^2 + 122980^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31212212321 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31212212293 and 31212212302.

It is not an unprimeable number, because it can be changed into a prime (31212212821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3877130 + ... + 3885171.

It is an arithmetic number, because the mean of its divisors is an integer number (7804994661).

Almost surely, 2^31212212321 is an apocalyptic number.

It is an amenable number.

31212212321 is a deficient number, since it is larger than the sum of its proper divisors (7766323).

31212212321 is an equidigital number, since it uses as much as digits as its factorization.

31212212321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7766322.

The product of its digits is 288, while the sum is 20.

Adding to 31212212321 its reverse (12321221213), we get a palindrome (43533433534).

The spelling of 31212212321 in words is "thirty-one billion, two hundred twelve million, two hundred twelve thousand, three hundred twenty-one".