21000012020100 has 216 divisors, whose sum is σ = 65951820480000. Its totient is φ = 5589084084480.

The previous prime is 21000012020027. The next prime is 21000012020129. The reversal of 21000012020100 is 102021000012.

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

It is an unprimeable number.

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 71 ways as a sum of consecutive naturals, for example, 1339364061 + ... + 1339379739.

Almost surely, 2^{21000012020100} is an apocalyptic number.

21000012020100 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 21000012020100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32975910240000).

21000012020100 is an abundant number, since it is smaller than the sum of its proper divisors (44951808459900).

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

21000012020100 is a wasteful number, since it uses less digits than its factorization.

21000012020100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18507 (or 18497 counting only the distinct ones).

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

Adding to 21000012020100 its reverse (102021000012), we get a palindrome (21102033020112).

The spelling of 21000012020100 in words is "twenty-one trillion, twelve million, twenty thousand, one hundred".