21025806 has 32 divisors (see below), whose sum is σ = 43058688. Its totient is φ = 6842880.

The previous prime is 21025793. The next prime is 21025811. The reversal of 21025806 is 60852012.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 77451 + ... + 77721.

It is an arithmetic number, because the mean of its divisors is an integer number (1345584).

Almost surely, 2^21025806 is an apocalyptic number.

21025806 is an abundant number, since it is smaller than the sum of its proper divisors (22032882).

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

21025806 is a wasteful number, since it uses less digits than its factorization.

21025806 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 536.

The product of its (nonzero) digits is 960, while the sum is 24.

The square root of 21025806 is about 4585.3904959120. The cubic root of 21025806 is about 276.0053821677.

Adding to 21025806 its reverse (60852012), we get a palindrome (81877818).

The spelling of 21025806 in words is "twenty-one million, twenty-five thousand, eight hundred six".