21002100111220 has 12 divisors (see below), whose sum is σ = 44104410233604. Its totient is φ = 8400840044480.

The previous prime is 21002100111193. The next prime is 21002100111301. The reversal of 21002100111220 is 2211100120012.

It can be written as a sum of positive squares in 2 ways, for example, as 3122953427344 + 17879146683876 = 1767188^2 + 4228374^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21002100111220.

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, 525052502761 + ... + 525052502800.

It is an arithmetic number, because the mean of its divisors is an integer number (3675367519467).

Almost surely, 2^{21002100111220} is an apocalyptic number.

21002100111220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21002100111220 is an abundant number, since it is smaller than the sum of its proper divisors (23102310122384).

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

21002100111220 is a wasteful number, since it uses less digits than its factorization.

21002100111220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1050105005570 (or 1050105005568 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21002100111220 its reverse (2211100120012), we get a palindrome (23213200231232).

The spelling of 21002100111220 in words is "twenty-one trillion, two billion, one hundred million, one hundred eleven thousand, two hundred twenty".