20665728 has 48 divisors (see below), whose sum is σ = 59471100. Its totient is φ = 6888192.

The previous prime is 20665669. The next prime is 20665739. The reversal of 20665728 is 82756602.

20665728 is a `hidden beast` number, since 20 + 66 + 572 + 8 = 666.

It is a tau number, because it is divible by the number of its divisors (48).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 20665692 and 20665701.

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 5 ways as a sum of consecutive naturals, for example, 7818 + ... + 10121.

Almost surely, 2^20665728 is an apocalyptic number.

It is an amenable number.

20665728 is an abundant number, since it is smaller than the sum of its proper divisors (38805372).

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

20665728 is a wasteful number, since it uses less digits than its factorization.

20665728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17959 (or 17944 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 36.

The square root of 20665728 is about 4545.9573249207. The cubic root of 20665728 is about 274.4207222264.

The spelling of 20665728 in words is "twenty million, six hundred sixty-five thousand, seven hundred twenty-eight".