21102102120 has 128 divisors (see below), whose sum is σ = 69337658880. Its totient is φ = 5095200000.

The previous prime is 21102102113. The next prime is 21102102121. The reversal of 21102102120 is 2120120112.

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 = 21102102096 and 21102102105.

It is not an unprimeable number, because it can be changed into a prime (21102102121) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 299475 + ... + 363165.

It is an arithmetic number, because the mean of its divisors is an integer number (541700460).

Almost surely, 2^21102102120 is an apocalyptic number.

21102102120 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 21102102120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34668829440).

21102102120 is an abundant number, since it is smaller than the sum of its proper divisors (48235556760).

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

21102102120 is a wasteful number, since it uses less digits than its factorization.

21102102120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63967 (or 63963 counting only the distinct ones).

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

Adding to 21102102120 its reverse (2120120112), we get a palindrome (23222222232).

The spelling of 21102102120 in words is "twenty-one billion, one hundred two million, one hundred two thousand, one hundred twenty".