21100221020 has 12 divisors (see below), whose sum is σ = 44310464184. Its totient is φ = 8440088400.

The previous prime is 21100221019. The next prime is 21100221047. The reversal of 21100221020 is 2012200112.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21100220992 and 21100221010.

It is a congruent number.

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 3 ways as a sum of consecutive naturals, for example, 527505506 + ... + 527505545.

It is an arithmetic number, because the mean of its divisors is an integer number (3692538682).

Almost surely, 2^21100221020 is an apocalyptic number.

21100221020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21100221020 is an abundant number, since it is smaller than the sum of its proper divisors (23210243164).

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

21100221020 is a wasteful number, since it uses less digits than its factorization.

21100221020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1055011060 (or 1055011058 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 21100221020 its reverse (2012200112), we get a palindrome (23112421132).

The spelling of 21100221020 in words is "twenty-one billion, one hundred million, two hundred twenty-one thousand, twenty".