20971808 has 48 divisors (see below), whose sum is σ = 48517056. Its totient is φ = 8797440.

The previous prime is 20971807. The next prime is 20971889. The reversal of 20971808 is 80817902.

It is a happy number.

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

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2285 + ... + 6867.

It is an arithmetic number, because the mean of its divisors is an integer number (1010772).

Almost surely, 2^20971808 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20971808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24258528).

20971808 is an abundant number, since it is smaller than the sum of its proper divisors (27545248).

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

20971808 is a wasteful number, since it uses less digits than its factorization.

20971808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4617 (or 4609 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 35.

The square root of 20971808 is about 4579.4986625175. The cubic root of 20971808 is about 275.7689026824.

The spelling of 20971808 in words is "twenty million, nine hundred seventy-one thousand, eight hundred eight".