21002100021000 has 384 divisors, whose sum is σ = 81139017772800. Its totient is φ = 4799834726400.

The previous prime is 21002100020987. The next prime is 21002100021047. The reversal of 21002100021000 is 12000120012.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 593379304 + ... + 593414696.

It is an arithmetic number, because the mean of its divisors is an integer number (211299525450).

Almost surely, 2^{21002100021000} is an apocalyptic number.

21002100021000 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 21002100021000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40569508886400).

21002100021000 is an abundant number, since it is smaller than the sum of its proper divisors (60136917751800).

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

21002100021000 is a wasteful number, since it uses less digits than its factorization.

21002100021000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44846 (or 44829 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

Adding to 21002100021000 its reverse (12000120012), we get a palindrome (21014100141012).

The spelling of 21002100021000 in words is "twenty-one trillion, two billion, one hundred million, twenty-one thousand".