21100220120020 has 48 divisors (see below), whose sum is σ = 45663360332688. Its totient is φ = 8183950248960.

The previous prime is 21100220120017. The next prime is 21100220120039. The reversal of 21100220120020 is 2002102200112.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 7930317830724 + 13169902289296 = 2816082^2 + 3629036^2 .

It is a super-2 number, since 2×21100220120020² (a number of 27 digits) contains 22 as substring.

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, 48441561 + ... + 48875200.

It is an arithmetic number, because the mean of its divisors is an integer number (951320006931).

Almost surely, 2^{21100220120020} is an apocalyptic number.

21100220120020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21100220120020 is an abundant number, since it is smaller than the sum of its proper divisors (24563140212668).

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

21100220120020 is a wasteful number, since it uses less digits than its factorization.

21100220120020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 97317100 (or 97317098 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 13.

Adding to 21100220120020 its reverse (2002102200112), we get a palindrome (23102322320132).

The spelling of 21100220120020 in words is "twenty-one trillion, one hundred billion, two hundred twenty million, one hundred twenty thousand, twenty".