20728603 has 4 divisors (see below), whose sum is σ = 23689840. Its totient is φ = 17767368.

The previous prime is 20728597. The next prime is 20728619. The reversal of 20728603 is 30682702.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 30682702 = 2 ⋅15341351.

It is a cyclic number.

It is not a de Polignac number, because 20728603 - 2⁵ = 20728571 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20728633) by changing a digit.

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, 1480608 + ... + 1480621.

It is an arithmetic number, because the mean of its divisors is an integer number (5922460).

Almost surely, 2^20728603 is an apocalyptic number.

20728603 is a deficient number, since it is larger than the sum of its proper divisors (2961237).

20728603 is an equidigital number, since it uses as much as digits as its factorization.

20728603 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2961236.

The product of its (nonzero) digits is 4032, while the sum is 28.

The square root of 20728603 is about 4552.8675579243. The cubic root of 20728603 is about 274.6987466916.

The spelling of 20728603 in words is "twenty million, seven hundred twenty-eight thousand, six hundred three".