21221102100020 has 48 divisors (see below), whose sum is σ = 46102231198800. Its totient is φ = 8195519754240.

The previous prime is 21221102100007. The next prime is 21221102100091. The reversal of 21221102100020 is 2000120112212.

It can be written as a sum of positive squares in 8 ways, for example, as 7267186675984 + 13953915424036 = 2695772^2 + 3735494^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21221102099968 and 21221102100004.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 22459286 + ... + 23385074.

It is an arithmetic number, because the mean of its divisors is an integer number (960463149975).

Almost surely, 2^{21221102100020} is an apocalyptic number.

21221102100020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21221102100020 is an abundant number, since it is smaller than the sum of its proper divisors (24881129098780).

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

21221102100020 is a wasteful number, since it uses less digits than its factorization.

21221102100020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 965348 (or 965346 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21221102100020 its reverse (2000120112212), we get a palindrome (23221222212232).

The spelling of 21221102100020 in words is "twenty-one trillion, two hundred twenty-one billion, one hundred two million, one hundred thousand, twenty".