21100121020020 has 192 divisors, whose sum is σ = 67936903888896. Its totient is φ = 4793144025600.

The previous prime is 21100121019977. The next prime is 21100121020037. The reversal of 21100121020020 is 2002012100112.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21100121019978 and 21100121020005.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 441928269 + ... + 441976011.

It is an arithmetic number, because the mean of its divisors is an integer number (353838041088).

Almost surely, 2^{21100121020020} is an apocalyptic number.

21100121020020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21100121020020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33968451944448).

21100121020020 is an abundant number, since it is smaller than the sum of its proper divisors (46836782868876).

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

21100121020020 is a wasteful number, since it uses less digits than its factorization.

21100121020020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54230 (or 54228 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 21100121020020 its reverse (2002012100112), we get a palindrome (23102133120132).

The spelling of 21100121020020 in words is "twenty-one trillion, one hundred billion, one hundred twenty-one million, twenty thousand, twenty".