201311809 has 4 divisors (see below), whose sum is σ = 201346180. Its totient is φ = 201277440.

The previous prime is 201311797. The next prime is 201311843. The reversal of 201311809 is 908113102.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 129960000 + 71351809 = 11400^2 + 8447^2 .

It is a cyclic number.

It is not a de Polignac number, because 201311809 - 2⁵ = 201311777 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (201311309) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5952 + ... + 20929.

It is an arithmetic number, because the mean of its divisors is an integer number (50336545).

Almost surely, 2^201311809 is an apocalyptic number.

It is an amenable number.

201311809 is a deficient number, since it is larger than the sum of its proper divisors (34371).

201311809 is an equidigital number, since it uses as much as digits as its factorization.

201311809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34370.

The product of its (nonzero) digits is 432, while the sum is 25.

The square root of 201311809 is about 14188.4392728728. The cubic root of 201311809 is about 586.0793466157.

The spelling of 201311809 in words is "two hundred one million, three hundred eleven thousand, eight hundred nine".