1865665681 has 16 divisors (see below), whose sum is σ = 2093345856. Its totient is φ = 1648000000.

The previous prime is 1865665673. The next prime is 1865665741.

1865665681 is nontrivially palindromic in base 10.

It is a cyclic number.

It is not a de Polignac number, because 1865665681 - 2³ = 1865665673 is a prime.

It is a super-2 number, since 2×1865665681² = 6961416866522387522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1865665661) 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, 104961 + ... + 121441.

It is an arithmetic number, because the mean of its divisors is an integer number (130834116).

Almost surely, 2^1865665681 is an apocalyptic number.

1865665681 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1865665681 is a deficient number, since it is larger than the sum of its proper divisors (227680175).

1865665681 is a wasteful number, since it uses less digits than its factorization.

1865665681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16784.

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

The square root of 1865665681 is about 43193.3522778679. The cubic root of 1865665681 is about 1231.0563734238.

The spelling of 1865665681 in words is "one billion, eight hundred sixty-five million, six hundred sixty-five thousand, six hundred eighty-one".