1681887409 has 2 divisors, whose sum is σ = 1681887410. Its totient is φ = 1681887408.

The previous prime is 1681887373. The next prime is 1681887419. The reversal of 1681887409 is 9047881861.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1664640000 + 17247409 = 40800^2 + 4153^2 .

It is an emirp because it is prime and its reverse (9047881861) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1681887409 - 2¹⁵ = 1681854641 is a prime.

It is not a weakly prime, because it can be changed into another prime (1681887419) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 840943704 + 840943705.

It is an arithmetic number, because the mean of its divisors is an integer number (840943705).

Almost surely, 2^1681887409 is an apocalyptic number.

It is an amenable number.

1681887409 is a deficient number, since it is larger than the sum of its proper divisors (1).

1681887409 is an equidigital number, since it uses as much as digits as its factorization.

1681887409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 774144, while the sum is 52.

The square root of 1681887409 is about 41010.8206330963. The cubic root of 1681887409 is about 1189.2294069493.

The spelling of 1681887409 in words is "one billion, six hundred eighty-one million, eight hundred eighty-seven thousand, four hundred nine".