1681287809 has 2 divisors, whose sum is σ = 1681287810. Its totient is φ = 1681287808.

The previous prime is 1681287793. The next prime is 1681287869. The reversal of 1681287809 is 9087821861.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 889709584 + 791578225 = 29828^2 + 28135^2 .

It is a cyclic number.

It is not a de Polignac number, because 1681287809 - 2⁴ = 1681287793 is a prime.

It is not a weakly prime, because it can be changed into another prime (1681287869) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 840643904 + 840643905.

It is an arithmetic number, because the mean of its divisors is an integer number (840643905).

Almost surely, 2^1681287809 is an apocalyptic number.

It is an amenable number.

1681287809 is a deficient number, since it is larger than the sum of its proper divisors (1).

1681287809 is an equidigital number, since it uses as much as digits as its factorization.

1681287809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 387072, while the sum is 50.

The square root of 1681287809 is about 41003.5097156329. The cubic root of 1681287809 is about 1189.0880683750.

The spelling of 1681287809 in words is "one billion, six hundred eighty-one million, two hundred eighty-seven thousand, eight hundred nine".