21001001100020 has 12 divisors (see below), whose sum is σ = 44102102310084. Its totient is φ = 8400400440000.

The previous prime is 21001001100019. The next prime is 21001001100031. The reversal of 21001001100020 is 2000110010012.

It can be written as a sum of positive squares in 2 ways, for example, as 9049917022864 + 11951084077156 = 3008308^2 + 3457034^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21001001099980 and 21001001100007.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 525025027481 + ... + 525025027520.

It is an arithmetic number, because the mean of its divisors is an integer number (3675175192507).

Almost surely, 2^{21001001100020} is an apocalyptic number.

21001001100020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21001001100020 is an abundant number, since it is smaller than the sum of its proper divisors (23101101210064).

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

21001001100020 is a wasteful number, since it uses less digits than its factorization.

21001001100020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1050050055010 (or 1050050055008 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 8.

Adding to 21001001100020 its reverse (2000110010012), we get a palindrome (23001111110032).

The spelling of 21001001100020 in words is "twenty-one trillion, one billion, one million, one hundred thousand, twenty".