21103120 has 80 divisors (see below), whose sum is σ = 53032320. Its totient is φ = 7780352.

The previous prime is 21103109. The next prime is 21103123. The reversal of 21103120 is 2130112.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a junction number, because it is equal to n+sod(n) for n = 21103097 and 21103106.

It is not an unprimeable number, because it can be changed into a prime (21103123) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 80109 + ... + 80371.

It is an arithmetic number, because the mean of its divisors is an integer number (662904).

Almost surely, 2^21103120 is an apocalyptic number.

21103120 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 21103120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26516160).

21103120 is an abundant number, since it is smaller than the sum of its proper divisors (31929200).

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

21103120 is a wasteful number, since it uses less digits than its factorization.

21103120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 352 (or 346 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 10.

The square root of 21103120 is about 4593.8132308573. The cubic root of 21103120 is about 276.3432681938.

Adding to 21103120 its reverse (2130112), we get a palindrome (23233232).

The spelling of 21103120 in words is "twenty-one million, one hundred three thousand, one hundred twenty".