20728133 has 2 divisors, whose sum is σ = 20728134. Its totient is φ = 20728132.

The previous prime is 20728121. The next prime is 20728139. The reversal of 20728133 is 33182702.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20593444 + 134689 = 4538^2 + 367^2 .

It is a cyclic number.

It is not a de Polignac number, because 20728133 - 2⁸ = 20727877 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20728139) 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 as a sum of consecutive naturals, namely, 10364066 + 10364067.

It is an arithmetic number, because the mean of its divisors is an integer number (10364067).

Almost surely, 2^20728133 is an apocalyptic number.

It is an amenable number.

20728133 is a deficient number, since it is larger than the sum of its proper divisors (1).

20728133 is an equidigital number, since it uses as much as digits as its factorization.

20728133 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2016, while the sum is 26.

The square root of 20728133 is about 4552.8159418101. The cubic root of 20728133 is about 274.6966705043.

The spelling of 20728133 in words is "twenty million, seven hundred twenty-eight thousand, one hundred thirty-three".