21064806 has 96 divisors (see below), whose sum is σ = 57456000. Its totient is φ = 5688144.

The previous prime is 21064783. The next prime is 21064837. The reversal of 21064806 is 60846012.

21064806 is a `hidden beast` number, since 2 + 10 + 648 + 0 + 6 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a self number, because there is not a number n which added to its sum of digits gives 21064806.

It is a congruent number.

It is an unprimeable number.

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 47 ways as a sum of consecutive naturals, for example, 50065 + ... + 50483.

It is an arithmetic number, because the mean of its divisors is an integer number (598500).

Almost surely, 2^21064806 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21064806, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28728000).

21064806 is an abundant number, since it is smaller than the sum of its proper divisors (36391194).

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

21064806 is a wasteful number, since it uses less digits than its factorization.

21064806 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 463 (or 450 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The square root of 21064806 is about 4589.6411624440. The cubic root of 21064806 is about 276.1759275342.

The spelling of 21064806 in words is "twenty-one million, sixty-four thousand, eight hundred six".