21112208100 has 108 divisors (see below), whose sum is σ = 66760984836. Its totient is φ = 5580072960.

The previous prime is 21112208041. The next prime is 21112208119. The reversal of 21112208100 is 180221112.

It can be written as a sum of positive squares in 6 ways, for example, as 1379825316 + 19732382784 = 37146^2 + 140472^2 .

It is a super-2 number, since 2×21112208100² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 2097 + ... + 205496.

It is an arithmetic number, because the mean of its divisors is an integer number (618157267).

Almost surely, 2^21112208100 is an apocalyptic number.

21112208100 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 21112208100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33380492418).

21112208100 is an abundant number, since it is smaller than the sum of its proper divisors (45648776736).

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

21112208100 is a wasteful number, since it uses less digits than its factorization.

21112208100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 207726 (or 207716 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 18.

Adding to 21112208100 its reverse (180221112), we get a palindrome (21292429212).

The spelling of 21112208100 in words is "twenty-one billion, one hundred twelve million, two hundred eight thousand, one hundred".