21101122020 has 96 divisors (see below), whose sum is σ = 64562795136. Its totient is φ = 5106816000.

The previous prime is 21101121997. The next prime is 21101122079. The reversal of 21101122020 is 2022110112.

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 = 21101121987 and 21101122005.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 370062 + ... + 423258.

It is an arithmetic number, because the mean of its divisors is an integer number (672529116).

Almost surely, 2^21101122020 is an apocalyptic number.

21101122020 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 21101122020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32281397568).

21101122020 is an abundant number, since it is smaller than the sum of its proper divisors (43461673116).

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

21101122020 is a wasteful number, since it uses less digits than its factorization.

21101122020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53821 (or 53819 counting only the distinct ones).

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

Adding to 21101122020 its reverse (2022110112), we get a palindrome (23123232132).

The spelling of 21101122020 in words is "twenty-one billion, one hundred one million, one hundred twenty-two thousand, twenty".