31221211121 has 4 divisors (see below), whose sum is σ = 31237215744. Its totient is φ = 31205206500.

The previous prime is 31221211097. The next prime is 31221211139. The reversal of 31221211121 is 12111212213.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31221211121 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 31221211121.

It is not an unprimeable number, because it can be changed into a prime (31221211171) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7999385 + ... + 8003286.

It is an arithmetic number, because the mean of its divisors is an integer number (7809303936).

Almost surely, 2^31221211121 is an apocalyptic number.

It is an amenable number.

31221211121 is a deficient number, since it is larger than the sum of its proper divisors (16004623).

31221211121 is a wasteful number, since it uses less digits than its factorization.

31221211121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16004622.

The product of its digits is 48, while the sum is 17.

Adding to 31221211121 its reverse (12111212213), we get a palindrome (43332423334).

The spelling of 31221211121 in words is "thirty-one billion, two hundred twenty-one million, two hundred eleven thousand, one hundred twenty-one".