31121220220 has 24 divisors (see below), whose sum is σ = 67120903584. Its totient is φ = 12112042176.

The previous prime is 31121220209. The next prime is 31121220223. The reversal of 31121220220 is 2202212113.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 31121220194 and 31121220203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31121220223) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21027112 + ... + 21028591.

It is an arithmetic number, because the mean of its divisors is an integer number (2796704316).

Almost surely, 2^31121220220 is an apocalyptic number.

It is an amenable number.

31121220220 is an abundant number, since it is smaller than the sum of its proper divisors (35999683364).

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

31121220220 is a wasteful number, since it uses less digits than its factorization.

31121220220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42055749 (or 42055747 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 16.

Adding to 31121220220 its reverse (2202212113), we get a palindrome (33323432333).

The spelling of 31121220220 in words is "thirty-one billion, one hundred twenty-one million, two hundred twenty thousand, two hundred twenty".