31221323320 has 128 divisors (see below), whose sum is σ = 80100887040. Its totient is φ = 10841290240.

The previous prime is 31221323299. The next prime is 31221323323. The reversal of 31221323320 is 2332312213.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a junction number, because it is equal to n+sod(n) for n = 31221323291 and 31221323300.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31221323323) 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 31 ways as a sum of consecutive naturals, for example, 6909702 + ... + 6914218.

It is an arithmetic number, because the mean of its divisors is an integer number (625788180).

Almost surely, 2^31221323320 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31221323320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40050443520).

31221323320 is an abundant number, since it is smaller than the sum of its proper divisors (48879563720).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

31221323320 is a wasteful number, since it uses less digits than its factorization.

31221323320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5245 (or 5241 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 22.

Adding to 31221323320 its reverse (2332312213), we get a palindrome (33553635533).

It can be divided in two parts, 312213 and 23320, that added together give a palindrome (335533).

The spelling of 31221323320 in words is "thirty-one billion, two hundred twenty-one million, three hundred twenty-three thousand, three hundred twenty".