21211100100 has 144 divisors (see below), whose sum is σ = 68245632000. Its totient is φ = 5651660160.

The previous prime is 21211100093. The next prime is 21211100111. The reversal of 21211100100 is 100111212.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 4417501 + ... + 4422299.

It is an arithmetic number, because the mean of its divisors is an integer number (473928000).

Almost surely, 2^21211100100 is an apocalyptic number.

21211100100 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 21211100100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34122816000).

21211100100 is an abundant number, since it is smaller than the sum of its proper divisors (47034531900).

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

21211100100 is a wasteful number, since it uses less digits than its factorization.

21211100100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6459 (or 6446 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 9.

Adding to 21211100100 its reverse (100111212), we get a palindrome (21311211312).

The spelling of 21211100100 in words is "twenty-one billion, two hundred eleven million, one hundred thousand, one hundred".