21100212120 has 512 divisors, whose sum is σ = 74680704000. Its totient is φ = 4724490240.

The previous prime is 21100212083. The next prime is 21100212131. The reversal of 21100212120 is 2121200112.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21100212096 and 21100212105.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 117878191 + ... + 117878369.

It is an arithmetic number, because the mean of its divisors is an integer number (145860750).

Almost surely, 2^21100212120 is an apocalyptic number.

21100212120 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 21100212120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37340352000).

21100212120 is an abundant number, since it is smaller than the sum of its proper divisors (53580491880).

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

21100212120 is a wasteful number, since it uses less digits than its factorization.

21100212120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 363 (or 359 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 21100212120 its reverse (2121200112), we get a palindrome (23221412232).

The spelling of 21100212120 in words is "twenty-one billion, one hundred million, two hundred twelve thousand, one hundred twenty".