21120210100 has 144 divisors (see below), whose sum is σ = 54647502336. Its totient is φ = 6994944000.

The previous prime is 21120210079. The next prime is 21120210107. The reversal of 21120210100 is 101202112.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21120210107) by changing a digit.

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 47 ways as a sum of consecutive naturals, for example, 561484 + ... + 597916.

It is an arithmetic number, because the mean of its divisors is an integer number (379496544).

Almost surely, 2^21120210100 is an apocalyptic number.

21120210100 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 21120210100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27323751168).

21120210100 is an abundant number, since it is smaller than the sum of its proper divisors (33527292236).

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

21120210100 is a wasteful number, since it uses less digits than its factorization.

21120210100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36506 (or 36499 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 21120210100 its reverse (101202112), we get a palindrome (21221412212).

The spelling of 21120210100 in words is "twenty-one billion, one hundred twenty million, two hundred ten thousand, one hundred".