21100100100 has 144 divisors (see below), whose sum is σ = 62925139200. Its totient is φ = 5456056320.

The previous prime is 21100100093. The next prime is 21100100143. The reversal of 21100100100 is 100100112.

It is a Harshad number since it is a multiple of its sum of digits (6).

It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.

21100100100 is a modest number, since divided by 100100 gives 21100 as remainder.

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, 1530036 + ... + 1543764.

Almost surely, 2^21100100100 is an apocalyptic number.

21100100100 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 21100100100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31462569600).

21100100100 is an abundant number, since it is smaller than the sum of its proper divisors (41825039100).

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

21100100100 is a wasteful number, since it uses less digits than its factorization.

21100100100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13902 (or 13895 counting only the distinct ones).

The product of its (nonzero) digits is 2, while the sum is 6.

Adding to 21100100100 its reverse (100100112), we get a palindrome (21200200212).

The spelling of 21100100100 in words is "twenty-one billion, one hundred million, one hundred thousand, one hundred".