31312431221 has 4 divisors (see below), whose sum is σ = 31340976012. Its totient is φ = 31283886432.

The previous prime is 31312431179. The next prime is 31312431239. The reversal of 31312431221 is 12213421313.

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 7108850596 + 24203580625 = 84314^2 + 155575^2 .

It is a cyclic number.

It is not a de Polignac number, because 31312431221 - 2²⁶ = 31245322357 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 (31312431251) 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, 14270750 + ... + 14272943.

It is an arithmetic number, because the mean of its divisors is an integer number (7835244003).

Almost surely, 2^31312431221 is an apocalyptic number.

It is an amenable number.

31312431221 is a deficient number, since it is larger than the sum of its proper divisors (28544791).

31312431221 is a wasteful number, since it uses less digits than its factorization.

31312431221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28544790.

The product of its digits is 864, while the sum is 23.

Adding to 31312431221 its reverse (12213421313), we get a palindrome (43525852534).

The spelling of 31312431221 in words is "thirty-one billion, three hundred twelve million, four hundred thirty-one thousand, two hundred twenty-one".