21031100220 has 144 divisors (see below), whose sum is σ = 64127064960. Its totient is φ = 5147520768.

The previous prime is 21031100149. The next prime is 21031100221. The reversal of 21031100220 is 2200113012.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21031100196 and 21031100205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21031100221) 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 47 ways as a sum of consecutive naturals, for example, 1809267 + ... + 1820853.

It is an arithmetic number, because the mean of its divisors is an integer number (445326840).

Almost surely, 2^21031100220 is an apocalyptic number.

21031100220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21031100220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32063532480).

21031100220 is an abundant number, since it is smaller than the sum of its proper divisors (43095964740).

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

21031100220 is a wasteful number, since it uses less digits than its factorization.

21031100220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11804 (or 11789 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 12.

Adding to 21031100220 its reverse (2200113012), we get a palindrome (23231213232).

The spelling of 21031100220 in words is "twenty-one billion, thirty-one million, one hundred thousand, two hundred twenty".