2081809 has 2 divisors, whose sum is σ = 2081810. Its totient is φ = 2081808.

The previous prime is 2081801. The next prime is 2081813. The reversal of 2081809 is 9081802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1587600 + 494209 = 1260^2 + 703^2 .

It is a cyclic number.

It is not a de Polignac number, because 2081809 - 2³ = 2081801 is a prime.

It is not a weakly prime, because it can be changed into another prime (2081801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1040904 + 1040905.

It is an arithmetic number, because the mean of its divisors is an integer number (1040905).

2^2081809 is an apocalyptic number.

It is an amenable number.

2081809 is a deficient number, since it is larger than the sum of its proper divisors (1).

2081809 is an equidigital number, since it uses as much as digits as its factorization.

2081809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1152, while the sum is 28.

The square root of 2081809 is about 1442.8475317926. The cubic root of 2081809 is about 127.6870815050.

The spelling of 2081809 in words is "two million, eighty-one thousand, eight hundred nine".