18195831809 has 2 divisors, whose sum is σ = 18195831810. Its totient is φ = 18195831808.

The previous prime is 18195831803. The next prime is 18195831839. The reversal of 18195831809 is 90813859181.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11811342400 + 6384489409 = 108680^2 + 79903^2 .

It is a cyclic number.

It is not a de Polignac number, because 18195831809 - 2¹⁶ = 18195766273 is a prime.

It is not a weakly prime, because it can be changed into another prime (18195831803) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9097915904 + 9097915905.

It is an arithmetic number, because the mean of its divisors is an integer number (9097915905).

Almost surely, 2^18195831809 is an apocalyptic number.

It is an amenable number.

18195831809 is a deficient number, since it is larger than the sum of its proper divisors (1).

18195831809 is an equidigital number, since it uses as much as digits as its factorization.

18195831809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 622080, while the sum is 53.

The spelling of 18195831809 in words is "eighteen billion, one hundred ninety-five million, eight hundred thirty-one thousand, eight hundred nine".