64091809 has 4 divisors (see below), whose sum is σ = 64187716. Its totient is φ = 63995904.

The previous prime is 64091791. The next prime is 64091843. The reversal of 64091809 is 90819046.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90819046 = 2 ⋅45409523.

It can be written as a sum of positive squares in 2 ways, for example, as 18731584 + 45360225 = 4328^2 + 6735^2 .

It is a cyclic number.

It is not a de Polignac number, because 64091809 - 2¹⁵ = 64059041 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (64091899) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 46944 + ... + 48289.

It is an arithmetic number, because the mean of its divisors is an integer number (16046929).

Almost surely, 2^64091809 is an apocalyptic number.

It is an amenable number.

64091809 is a deficient number, since it is larger than the sum of its proper divisors (95907).

64091809 is an equidigital number, since it uses as much as digits as its factorization.

64091809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95906.

The product of its (nonzero) digits is 15552, while the sum is 37.

The square root of 64091809 is about 8005.7360061396. The cubic root of 64091809 is about 400.1911773635.

The spelling of 64091809 in words is "sixty-four million, ninety-one thousand, eight hundred nine".