20697728 has 32 divisors (see below), whose sum is σ = 41668020. Its totient is φ = 10240000.

The previous prime is 20697713. The next prime is 20697737. The reversal of 20697728 is 82779602.

It can be written as a sum of positive squares in 2 ways, for example, as 12902464 + 7795264 = 3592^2 + 2792^2 .

It is a tau number, because it is divible by the number of its divisors (32).

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 3 ways as a sum of consecutive naturals, for example, 12128 + ... + 13728.

Almost surely, 2^20697728 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 20697728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (20834010).

20697728 is an abundant number, since it is smaller than the sum of its proper divisors (20970292).

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

20697728 is a wasteful number, since it uses less digits than its factorization.

20697728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1716 (or 1704 counting only the distinct ones).

The product of its (nonzero) digits is 84672, while the sum is 41.

The square root of 20697728 is about 4549.4755741734. The cubic root of 20697728 is about 274.5622921150.

Multiplying 20697728 by its sum of digits (41), we get a palindrome (848606848).

The spelling of 20697728 in words is "twenty million, six hundred ninety-seven thousand, seven hundred twenty-eight".