21100210100 has 18 divisors (see below), whose sum is σ = 45787456134. Its totient is φ = 8440084000.

The previous prime is 21100210073. The next prime is 21100210121. The reversal of 21100210100 is 101200112.

It can be written as a sum of positive squares in 3 ways, for example, as 3326520976 + 17773689124 = 57676^2 + 133318^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 105500951 + ... + 105501150.

It is an arithmetic number, because the mean of its divisors is an integer number (2543747563).

Almost surely, 2^21100210100 is an apocalyptic number.

21100210100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21100210100 is an abundant number, since it is smaller than the sum of its proper divisors (24687246034).

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

21100210100 is a wasteful number, since it uses less digits than its factorization.

21100210100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 211002115 (or 211002108 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 8.

Adding to 21100210100 its reverse (101200112), we get a palindrome (21201410212).

The spelling of 21100210100 in words is "twenty-one billion, one hundred million, two hundred ten thousand, one hundred".