31130021220 has 24 divisors (see below), whose sum is σ = 87164059584. Its totient is φ = 8301338976.

The previous prime is 31130021201. The next prime is 31130021309. The reversal of 31130021220 is 2212003113.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 31130021220.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 259416784 + ... + 259416903.

It is an arithmetic number, because the mean of its divisors is an integer number (3631835816).

Almost surely, 2^31130021220 is an apocalyptic number.

31130021220 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

31130021220 is an abundant number, since it is smaller than the sum of its proper divisors (56034038364).

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

31130021220 is a wasteful number, since it uses less digits than its factorization.

31130021220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 518833699 (or 518833697 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 15.

Adding to 31130021220 its reverse (2212003113), we get a palindrome (33342024333).

It can be divided in two parts, 311300 and 21220, that added together give a triangular number (332520 = T₈₁₅).

The spelling of 31130021220 in words is "thirty-one billion, one hundred thirty million, twenty-one thousand, two hundred twenty".