20728017 has 12 divisors (see below), whose sum is σ = 29995524. Its totient is φ = 13793280.

The previous prime is 20728009. The next prime is 20728033. The reversal of 20728017 is 71082702.

It can be written as a sum of positive squares in 2 ways, for example, as 13242321 + 7485696 = 3639^2 + 2736^2 .

It is not a de Polignac number, because 20728017 - 2³ = 20728009 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20728067) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 3973 + ... + 7565.

It is an arithmetic number, because the mean of its divisors is an integer number (2499627).

Almost surely, 2^20728017 is an apocalyptic number.

It is an amenable number.

20728017 is a deficient number, since it is larger than the sum of its proper divisors (9267507).

20728017 is a wasteful number, since it uses less digits than its factorization.

20728017 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4240 (or 4237 counting only the distinct ones).

The product of its (nonzero) digits is 1568, while the sum is 27.

The square root of 20728017 is about 4552.8032024238. The cubic root of 20728017 is about 274.6961580788.

It can be divided in two parts, 207 and 28017, that added together give a square (28224 = 168²).

The spelling of 20728017 in words is "twenty million, seven hundred twenty-eight thousand, seventeen".