21265806 has 16 divisors (see below), whose sum is σ = 42613200. Its totient is φ = 7075008.

The previous prime is 21265789. The next prime is 21265817. The reversal of 21265806 is 60856212.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 300 + ... + 6528.

It is an arithmetic number, because the mean of its divisors is an integer number (2663325).

Almost surely, 2^21265806 is an apocalyptic number.

21265806 is an abundant number, since it is smaller than the sum of its proper divisors (21347394).

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

21265806 is a wasteful number, since it uses less digits than its factorization.

21265806 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6803.

The product of its (nonzero) digits is 5760, while the sum is 30.

The square root of 21265806 is about 4611.4863113751. The cubic root of 21265806 is about 277.0515702009.

The spelling of 21265806 in words is "twenty-one million, two hundred sixty-five thousand, eight hundred six".