20939728 has 20 divisors (see below), whose sum is σ = 40786948. Its totient is φ = 10414080.

The previous prime is 20939719. The next prime is 20939731. The reversal of 20939728 is 82793902.

It can be written as a sum of positive squares in 2 ways, for example, as 7011904 + 13927824 = 2648^2 + 3732^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 303 + ... + 6478.

Almost surely, 2^20939728 is an apocalyptic number.

It is an amenable number.

20939728 is a deficient number, since it is larger than the sum of its proper divisors (19847220).

20939728 is a wasteful number, since it uses less digits than its factorization.

20939728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6982 (or 6976 counting only the distinct ones).

The product of its (nonzero) digits is 54432, while the sum is 40.

The square root of 20939728 is about 4575.9947552417. The cubic root of 20939728 is about 275.6282188801.

The spelling of 20939728 in words is "twenty million, nine hundred thirty-nine thousand, seven hundred twenty-eight".