20748809 has 2 divisors, whose sum is σ = 20748810. Its totient is φ = 20748808.

The previous prime is 20748803. The next prime is 20748821. The reversal of 20748809 is 90884702.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20748025 + 784 = 4555^2 + 28^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20748809 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (20748803) 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, 10374404 + 10374405.

It is an arithmetic number, because the mean of its divisors is an integer number (10374405).

Almost surely, 2^20748809 is an apocalyptic number.

It is an amenable number.

20748809 is a deficient number, since it is larger than the sum of its proper divisors (1).

20748809 is an equidigital number, since it uses as much as digits as its factorization.

20748809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 32256, while the sum is 38.

The square root of 20748809 is about 4555.0860584626. The cubic root of 20748809 is about 274.7879754144.

The spelling of 20748809 in words is "twenty million, seven hundred forty-eight thousand, eight hundred nine".