1816020809 has 2 divisors, whose sum is σ = 1816020810. Its totient is φ = 1816020808.

The previous prime is 1816020797. The next prime is 1816020823. The reversal of 1816020809 is 9080206181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1001089600 + 814931209 = 31640^2 + 28547^2 .

It is a cyclic number.

It is not a de Polignac number, because 1816020809 - 2⁸ = 1816020553 is a prime.

It is not a weakly prime, because it can be changed into another prime (1816020839) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 908010404 + 908010405.

It is an arithmetic number, because the mean of its divisors is an integer number (908010405).

Almost surely, 2^1816020809 is an apocalyptic number.

It is an amenable number.

1816020809 is a deficient number, since it is larger than the sum of its proper divisors (1).

1816020809 is an equidigital number, since it uses as much as digits as its factorization.

1816020809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6912, while the sum is 35.

The square root of 1816020809 is about 42614.7956583157. The cubic root of 1816020809 is about 1220.0387000623.

The spelling of 1816020809 in words is "one billion, eight hundred sixteen million, twenty thousand, eight hundred nine".