1856681665 has 16 divisors (see below), whose sum is σ = 2238058368. Its totient is φ = 1478670336.

The previous prime is 1856681633. The next prime is 1856681669. The reversal of 1856681665 is 5661866581.

It is a cyclic number.

It is not a de Polignac number, because 1856681665 - 2⁵ = 1856681633 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1856681669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1609729 + ... + 1610881.

It is an arithmetic number, because the mean of its divisors is an integer number (139878648).

Almost surely, 2^1856681665 is an apocalyptic number.

It is an amenable number.

1856681665 is a deficient number, since it is larger than the sum of its proper divisors (381376703).

1856681665 is a wasteful number, since it uses less digits than its factorization.

1856681665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2328.

The product of its digits is 2073600, while the sum is 52.

The square root of 1856681665 is about 43089.2291065876. The cubic root of 1856681665 is about 1229.0771637878.

The spelling of 1856681665 in words is "one billion, eight hundred fifty-six million, six hundred eighty-one thousand, six hundred sixty-five".