21221112100 has 54 divisors (see below), whose sum is σ = 47200747622. Its totient is φ = 8281344000.

The previous prime is 21221112091. The next prime is 21221112131. The reversal of 21221112100 is 121112212.

It can be written as a sum of positive squares in 9 ways, for example, as 20407265316 + 813846784 = 142854^2 + 28528^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 104980 + ... + 231220.

Almost surely, 2^21221112100 is an apocalyptic number.

21221112100 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 21221112100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23600373811).

21221112100 is an abundant number, since it is smaller than the sum of its proper divisors (25979635522).

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

21221112100 is a wasteful number, since it uses less digits than its factorization.

21221112100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 126337 (or 126289 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21221112100 its reverse (121112212), we get a palindrome (21342224312).

The spelling of 21221112100 in words is "twenty-one billion, two hundred twenty-one million, one hundred twelve thousand, one hundred".