20835809 has 2 divisors, whose sum is σ = 20835810. Its totient is φ = 20835808.

The previous prime is 20835803. The next prime is 20835811. The reversal of 20835809 is 90853802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18464209 + 2371600 = 4297^2 + 1540^2 .

It is a cyclic number.

It is not a de Polignac number, because 20835809 - 2⁸ = 20835553 is a prime.

Together with 20835811, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20835803) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10417904 + 10417905.

It is an arithmetic number, because the mean of its divisors is an integer number (10417905).

Almost surely, 2^20835809 is an apocalyptic number.

It is an amenable number.

20835809 is a deficient number, since it is larger than the sum of its proper divisors (1).

20835809 is an equidigital number, since it uses as much as digits as its factorization.

20835809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 17280, while the sum is 35.

The square root of 20835809 is about 4564.6258335158. The cubic root of 20835809 is about 275.1715029378.

The spelling of 20835809 in words is "twenty million, eight hundred thirty-five thousand, eight hundred nine".