21101111220020 has 24 divisors (see below), whose sum is σ = 47720974605864. Its totient is φ = 7791179527296.

The previous prime is 21101111220019. The next prime is 21101111220047. The reversal of 21101111220020 is 2002211110112.

It can be written as a sum of positive squares in 4 ways, for example, as 4491296855824 + 16609814364196 = 2119268^2 + 4075514^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21101111219977 and 21101111220004.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 40579059779 + ... + 40579060298.

It is an arithmetic number, because the mean of its divisors is an integer number (1988373941911).

Almost surely, 2^{21101111220020} is an apocalyptic number.

21101111220020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21101111220020 is an abundant number, since it is smaller than the sum of its proper divisors (26619863385844).

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

21101111220020 is a wasteful number, since it uses less digits than its factorization.

21101111220020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 81158120099 (or 81158120097 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 21101111220020 its reverse (2002211110112), we get a palindrome (23103322330132).

The spelling of 21101111220020 in words is "twenty-one trillion, one hundred one billion, one hundred eleven million, two hundred twenty thousand, twenty".