21100031100 has 216 divisors, whose sum is σ = 70188195168. Its totient is φ = 5283532800.

The previous prime is 21100031087. The next prime is 21100031123. The reversal of 21100031100 is 113000112.

It is a super-2 number, since 2×21100031100² (a number of 21 digits) contains 22 as substring.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 7969977 + ... + 7972623.

It is an arithmetic number, because the mean of its divisors is an integer number (324945348).

Almost surely, 2^21100031100 is an apocalyptic number.

21100031100 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 21100031100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35094097584).

21100031100 is an abundant number, since it is smaller than the sum of its proper divisors (49088164068).

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

21100031100 is a wasteful number, since it uses less digits than its factorization.

21100031100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3205 (or 3195 counting only the distinct ones).

The product of its (nonzero) digits is 6, while the sum is 9.

Adding to 21100031100 its reverse (113000112), we get a palindrome (21213031212).

The spelling of 21100031100 in words is "twenty-one billion, one hundred million, thirty-one thousand, one hundred".