21001102100020 has 192 divisors, whose sum is σ = 53629890048000. Its totient is φ = 6743534174208.

The previous prime is 21001102099963. The next prime is 21001102100029. The reversal of 21001102100020 is 2000120110012.

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 (21001102100029) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1473857856 + ... + 1473872104.

It is an arithmetic number, because the mean of its divisors is an integer number (279322344000).

Almost surely, 2^{21001102100020} is an apocalyptic number.

21001102100020 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 21001102100020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26814945024000).

21001102100020 is an abundant number, since it is smaller than the sum of its proper divisors (32628787947980).

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

21001102100020 is a wasteful number, since it uses less digits than its factorization.

21001102100020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17282 (or 17280 counting only the distinct ones).

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

Adding to 21001102100020 its reverse (2000120110012), we get a palindrome (23001222210032).

The spelling of 21001102100020 in words is "twenty-one trillion, one billion, one hundred two million, one hundred thousand, twenty".