20728843 has 4 divisors (see below), whose sum is σ = 21289120. Its totient is φ = 20168568.

The previous prime is 20728817. The next prime is 20728847. The reversal of 20728843 is 34882702.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 34882702 = 2 ⋅17441351.

It is a cyclic number.

It is not a de Polignac number, because 20728843 - 2⁵ = 20728811 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20728799 and 20728808.

It is not an unprimeable number, because it can be changed into a prime (20728847) 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 3 ways as a sum of consecutive naturals, for example, 280083 + ... + 280156.

It is an arithmetic number, because the mean of its divisors is an integer number (5322280).

Almost surely, 2^20728843 is an apocalyptic number.

20728843 is a deficient number, since it is larger than the sum of its proper divisors (560277).

20728843 is an equidigital number, since it uses as much as digits as its factorization.

20728843 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 560276.

The product of its (nonzero) digits is 21504, while the sum is 34.

The square root of 20728843 is about 4552.8939148634. The cubic root of 20728843 is about 274.6998068602.

The spelling of 20728843 in words is "twenty million, seven hundred twenty-eight thousand, eight hundred forty-three".