20971806 has 8 divisors (see below), whose sum is σ = 41943624. Its totient is φ = 6990600.

The previous prime is 20971799. The next prime is 20971807. The reversal of 20971806 is 60817902.

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

20971806 is an admirable number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20971807) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1747645 + ... + 1747656.

It is an arithmetic number, because the mean of its divisors is an integer number (5242953).

Almost surely, 2^20971806 is an apocalyptic number.

20971806 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

20971806 is a wasteful number, since it uses less digits than its factorization.

20971806 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3495306.

The product of its (nonzero) digits is 6048, while the sum is 33.

The square root of 20971806 is about 4579.4984441530. The cubic root of 20971806 is about 275.7688939160.

The spelling of 20971806 in words is "twenty million, nine hundred seventy-one thousand, eight hundred six".