21021321100 has 288 divisors, whose sum is σ = 53790682176. Its totient is φ = 7060684800.

The previous prime is 21021321073. The next prime is 21021321103. The reversal of 21021321100 is 112312012.

It is a Harshad number since it is a multiple of its sum of digits (13).

It is not an unprimeable number, because it can be changed into a prime (21021321103) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 153440232 + ... + 153440368.

It is an arithmetic number, because the mean of its divisors is an integer number (186773202).

Almost surely, 2^21021321100 is an apocalyptic number.

21021321100 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 21021321100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26895341088).

21021321100 is an abundant number, since it is smaller than the sum of its proper divisors (32769361076).

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

21021321100 is a wasteful number, since it uses less digits than its factorization.

21021321100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 365 (or 358 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 13.

Adding to 21021321100 its reverse (112312012), we get a palindrome (21133633112).

The spelling of 21021321100 in words is "twenty-one billion, twenty-one million, three hundred twenty-one thousand, one hundred".