21021102120 has 128 divisors (see below), whose sum is σ = 64677191040. Its totient is φ = 5462768640.

The previous prime is 21021102107. The next prime is 21021102209. The reversal of 21021102120 is 2120112012.

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 = 21021102096 and 21021102105.

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, 2374342 + ... + 2383178.

It is an arithmetic number, because the mean of its divisors is an integer number (505290555).

Almost surely, 2^21021102120 is an apocalyptic number.

21021102120 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 21021102120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32338595520).

21021102120 is an abundant number, since it is smaller than the sum of its proper divisors (43656088920).

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

21021102120 is a wasteful number, since it uses less digits than its factorization.

21021102120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9355 (or 9351 counting only the distinct ones).

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

Adding to 21021102120 its reverse (2120112012), we get a palindrome (23141214132).

The spelling of 21021102120 in words is "twenty-one billion, twenty-one million, one hundred two thousand, one hundred twenty".