20397728 has 24 divisors (see below), whose sum is σ = 43247988. Its totient is φ = 9414144.

The previous prime is 20397719. The next prime is 20397737. The reversal of 20397728 is 82779302.

It is an interprime number because it is at equal distance from previous prime (20397719) and next prime (20397737).

It can be written as a sum of positive squares in 2 ways, for example, as 17875984 + 2521744 = 4228^2 + 1588^2 .

It is a junction number, because it is equal to n+sod(n) for n = 20397691 and 20397700.

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, 24101 + ... + 24932.

Almost surely, 2^20397728 is an apocalyptic number.

It is an amenable number.

20397728 is an abundant number, since it is smaller than the sum of its proper divisors (22850260).

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

20397728 is a wasteful number, since it uses less digits than its factorization.

20397728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49056 (or 49048 counting only the distinct ones).

The product of its (nonzero) digits is 42336, while the sum is 38.

The square root of 20397728 is about 4516.3843946236. The cubic root of 20397728 is about 273.2292974418.

The spelling of 20397728 in words is "twenty million, three hundred ninety-seven thousand, seven hundred twenty-eight".