21106123 has 4 divisors (see below), whose sum is σ = 21123648. Its totient is φ = 21088600.

The previous prime is 21106121. The next prime is 21106147. The reversal of 21106123 is 32160112.

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 21106123 - 2¹ = 21106121 is a prime.

It is a super-2 number, since 2×21106123² = 890936856182258, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21106097 and 21106106.

It is not an unprimeable number, because it can be changed into a prime (21106121) 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, 6811 + ... + 9412.

It is an arithmetic number, because the mean of its divisors is an integer number (5280912).

Almost surely, 2^21106123 is an apocalyptic number.

21106123 is a deficient number, since it is larger than the sum of its proper divisors (17525).

21106123 is a wasteful number, since it uses less digits than its factorization.

21106123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17524.

The product of its (nonzero) digits is 72, while the sum is 16.

The square root of 21106123 is about 4594.1400718742. The cubic root of 21106123 is about 276.3563755680.

Adding to 21106123 its reverse (32160112), we get a palindrome (53266235).

The spelling of 21106123 in words is "twenty-one million, one hundred six thousand, one hundred twenty-three".