21112123 has 4 divisors (see below), whose sum is σ = 21143368. Its totient is φ = 21080880.

The previous prime is 21112121. The next prime is 21112127. The reversal of 21112123 is 32121112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21112123 - 2¹ = 21112121 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21112121) 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 3 ways as a sum of consecutive naturals, for example, 14586 + ... + 15967.

It is an arithmetic number, because the mean of its divisors is an integer number (5285842).

Almost surely, 2^21112123 is an apocalyptic number.

21112123 is a deficient number, since it is larger than the sum of its proper divisors (31245).

21112123 is an equidigital number, since it uses as much as digits as its factorization.

21112123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31244.

The product of its digits is 24, while the sum is 13.

The square root of 21112123 is about 4594.7930312474. The cubic root of 21112123 is about 276.3825604047.

Adding to 21112123 its reverse (32121112), we get a palindrome (53233235).

The spelling of 21112123 in words is "twenty-one million, one hundred twelve thousand, one hundred twenty-three".