21002120102100 has 144 divisors (see below), whose sum is σ = 61255076299200. Its totient is φ = 5555654661120.

The previous prime is 21002120102069. The next prime is 21002120102101. The reversal of 21002120102100 is 120102120012.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21002120102101) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 21485182 + ... + 22441418.

It is an arithmetic number, because the mean of its divisors is an integer number (425382474300).

Almost surely, 2^{21002120102100} is an apocalyptic number.

21002120102100 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 21002120102100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30627538149600).

21002120102100 is an abundant number, since it is smaller than the sum of its proper divisors (40252956197100).

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

21002120102100 is a wasteful number, since it uses less digits than its factorization.

21002120102100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 956842 (or 956835 counting only the distinct ones).

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

Adding to 21002120102100 its reverse (120102120012), we get a palindrome (21122222222112).

The spelling of 21002120102100 in words is "twenty-one trillion, two billion, one hundred twenty million, one hundred two thousand, one hundred".