31321223221 has 4 divisors (see below), whose sum is σ = 31631334444. Its totient is φ = 31011112000.

The previous prime is 31321223203. The next prime is 31321223237. The reversal of 31321223221 is 12232212313.

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 15131460100 + 16189763121 = 123010^2 + 127239^2 .

It is a cyclic number.

It is not a de Polignac number, because 31321223221 - 2¹⁷ = 31321092149 is a prime.

It is a super-2 number, since 2×31321223221² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31321223192 and 31321223201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31321223251) 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, 155055460 + ... + 155055661.

It is an arithmetic number, because the mean of its divisors is an integer number (7907833611).

Almost surely, 2^31321223221 is an apocalyptic number.

It is an amenable number.

31321223221 is a deficient number, since it is larger than the sum of its proper divisors (310111223).

31321223221 is a wasteful number, since it uses less digits than its factorization.

31321223221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 310111222.

The product of its digits is 864, while the sum is 22.

Adding to 31321223221 its reverse (12232212313), we get a palindrome (43553435534).

The spelling of 31321223221 in words is "thirty-one billion, three hundred twenty-one million, two hundred twenty-three thousand, two hundred twenty-one".