20570809 has 16 divisors (see below), whose sum is σ = 24910848. Its totient is φ = 16605072.

The previous prime is 20570789. The next prime is 20570821. The reversal of 20570809 is 90807502.

It is a cyclic number.

It is not a de Polignac number, because 20570809 - 2⁷ = 20570681 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20570839) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9834 + ... + 11740.

It is an arithmetic number, because the mean of its divisors is an integer number (1556928).

Almost surely, 2^20570809 is an apocalyptic number.

It is an amenable number.

20570809 is a deficient number, since it is larger than the sum of its proper divisors (4340039).

20570809 is a wasteful number, since it uses less digits than its factorization.

20570809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2004.

The product of its (nonzero) digits is 5040, while the sum is 31.

The square root of 20570809 is about 4535.5053742665. The cubic root of 20570809 is about 273.9999334008. Note that the first 4 decimals are identical.

The spelling of 20570809 in words is "twenty million, five hundred seventy thousand, eight hundred nine".