21320806 has 24 divisors (see below), whose sum is σ = 35456400. Its totient is φ = 9558432.

The previous prime is 21320801. The next prime is 21320813. The reversal of 21320806 is 60802312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21320801) 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 11 ways as a sum of consecutive naturals, for example, 35295 + ... + 35893.

It is an arithmetic number, because the mean of its divisors is an integer number (1477350).

Almost surely, 2^21320806 is an apocalyptic number.

21320806 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21320806 is a deficient number, since it is larger than the sum of its proper divisors (14135594).

21320806 is a wasteful number, since it uses less digits than its factorization.

21320806 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 688 (or 651 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 22.

The square root of 21320806 is about 4617.4458307597. The cubic root of 21320806 is about 277.2902118118.

The spelling of 21320806 in words is "twenty-one million, three hundred twenty thousand, eight hundred six".