21231100000 has 144 divisors (see below), whose sum is σ = 56997570672. Its totient is φ = 7720000000.

The previous prime is 21231099949. The next prime is 21231100031. The reversal of 21231100000 is 113212.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a self number, because there is not a number n which added to its sum of digits gives 21231100000.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1090350 + ... + 1109650.

It is an arithmetic number, because the mean of its divisors is an integer number (395816463).

Almost surely, 2^21231100000 is an apocalyptic number.

21231100000 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 21231100000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28498785336).

21231100000 is an abundant number, since it is smaller than the sum of its proper divisors (35766470672).

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

21231100000 is an equidigital number, since it uses as much as digits as its factorization.

21231100000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19347 (or 19319 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 10.

Adding to 21231100000 its reverse (113212), we get a palindrome (21231213212).

The spelling of 21231100000 in words is "twenty-one billion, two hundred thirty-one million, one hundred thousand".