21110905 has 8 divisors (see below), whose sum is σ = 26017992. Its totient is φ = 16432128.

The previous prime is 21110899. The next prime is 21110909. The reversal of 21110905 is 50901112.

It can be written as a sum of positive squares in 4 ways, for example, as 1432809 + 19678096 = 1197^2 + 4436^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21110905 - 2⁹ = 21110393 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21110909) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 56872 + ... + 57241.

It is an arithmetic number, because the mean of its divisors is an integer number (3252249).

Almost surely, 2^21110905 is an apocalyptic number.

It is an amenable number.

21110905 is a deficient number, since it is larger than the sum of its proper divisors (4907087).

21110905 is a wasteful number, since it uses less digits than its factorization.

21110905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 114155.

The product of its (nonzero) digits is 90, while the sum is 19.

The square root of 21110905 is about 4594.6604880013. The cubic root of 21110905 is about 276.3772452842.

The spelling of 21110905 in words is "twenty-one million, one hundred ten thousand, nine hundred five".