31320443221 has 4 divisors (see below), whose sum is σ = 33162822252. Its totient is φ = 29478064192.

The previous prime is 31320443183. The next prime is 31320443251. The reversal of 31320443221 is 12234402313.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12234402313 = 7 ⋅1747771759.

It can be written as a sum of positive squares in 2 ways, for example, as 23557952196 + 7762491025 = 153486^2 + 88105^2 .

It is not a de Polignac number, because 31320443221 - 2⁷ = 31320443093 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31320443251) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 921189490 + ... + 921189523.

It is an arithmetic number, because the mean of its divisors is an integer number (8290705563).

Almost surely, 2^31320443221 is an apocalyptic number.

It is an amenable number.

31320443221 is a deficient number, since it is larger than the sum of its proper divisors (1842379031).

31320443221 is a wasteful number, since it uses less digits than its factorization.

31320443221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1842379030.

The product of its (nonzero) digits is 3456, while the sum is 25.

Adding to 31320443221 its reverse (12234402313), we get a palindrome (43554845534).

The spelling of 31320443221 in words is "thirty-one billion, three hundred twenty million, four hundred forty-three thousand, two hundred twenty-one".