21310031220 has 24 divisors (see below), whose sum is σ = 59668087584. Its totient is φ = 5682674976.

The previous prime is 21310031213. The next prime is 21310031269. The reversal of 21310031220 is 2213001312.

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 21310031220.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 177583534 + ... + 177583653.

It is an arithmetic number, because the mean of its divisors is an integer number (2486170316).

Almost surely, 2^21310031220 is an apocalyptic number.

21310031220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21310031220 is an abundant number, since it is smaller than the sum of its proper divisors (38358056364).

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

21310031220 is a wasteful number, since it uses less digits than its factorization.

21310031220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 355167199 (or 355167197 counting only the distinct ones).

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

Adding to 21310031220 its reverse (2213001312), we get a palindrome (23523032532).

The spelling of 21310031220 in words is "twenty-one billion, three hundred ten million, thirty-one thousand, two hundred twenty".