21102010020 has 288 divisors, whose sum is σ = 78966800640. Its totient is φ = 4441789440.

The previous prime is 21102010009. The next prime is 21102010043. The reversal of 21102010020 is 2001020112.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 21102009984 and 21102010011.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 8336155 + ... + 8338685.

It is an arithmetic number, because the mean of its divisors is an integer number (274190280).

Almost surely, 2^21102010020 is an apocalyptic number.

21102010020 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 21102010020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39483400320).

21102010020 is an abundant number, since it is smaller than the sum of its proper divisors (57864790620).

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

21102010020 is a wasteful number, since it uses less digits than its factorization.

21102010020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3075 (or 3070 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

Adding to 21102010020 its reverse (2001020112), we get a palindrome (23103030132).

The spelling of 21102010020 in words is "twenty-one billion, one hundred two million, ten thousand, twenty".