3131211221 has 4 divisors (see below), whose sum is σ = 3190290732. Its totient is φ = 3072131712.

The previous prime is 3131211211. The next prime is 3131211233. The reversal of 3131211221 is 1221121313.

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 1532331025 + 1598880196 = 39145^2 + 39986^2 .

It is a cyclic number.

It is not a de Polignac number, because 3131211221 - 2¹⁸ = 3130949077 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 3131211221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3131211211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 29539676 + ... + 29539781.

It is an arithmetic number, because the mean of its divisors is an integer number (797572683).

Almost surely, 2^3131211221 is an apocalyptic number.

It is an amenable number.

3131211221 is a deficient number, since it is larger than the sum of its proper divisors (59079511).

3131211221 is an equidigital number, since it uses as much as digits as its factorization.

3131211221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59079510.

The product of its digits is 72, while the sum is 17.

The square root of 3131211221 is about 55957.2267093358. The cubic root of 3131211221 is about 1462.9768531576.

Adding to 3131211221 its reverse (1221121313), we get a palindrome (4352332534).

The spelling of 3131211221 in words is "three billion, one hundred thirty-one million, two hundred eleven thousand, two hundred twenty-one".