21108123 has 24 divisors (see below), whose sum is σ = 31449600. Its totient is φ = 13635504.

The previous prime is 21108103. The next prime is 21108133. The reversal of 21108123 is 32180112.

It is not a de Polignac number, because 21108123 - 2¹⁷ = 20977051 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21108096 and 21108105.

It is not an unprimeable number, because it can be changed into a prime (21108103) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 58618 + ... + 58976.

It is an arithmetic number, because the mean of its divisors is an integer number (1310400).

Almost surely, 2^21108123 is an apocalyptic number.

21108123 is a deficient number, since it is larger than the sum of its proper divisors (10341477).

21108123 is a wasteful number, since it uses less digits than its factorization.

21108123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 551 (or 548 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 21108123 is about 4594.3577353097. The cubic root of 21108123 is about 276.3651043982.

Adding to 21108123 its reverse (32180112), we get a palindrome (53288235).

The spelling of 21108123 in words is "twenty-one million, one hundred eight thousand, one hundred twenty-three".