3865 has 4 divisors (see below), whose sum is σ = 4644.
Its totient is φ = 3088.
The previous prime is 3863. The next prime is 3877. The reversal of 3865 is 5683.
It is a semiprime because it is the product of two primes.
It can be written as a sum of positive squares in 2 ways, for example, as 729 + 3136 = 27^2 + 56^2
It is a cyclic number.
It is not a de Polignac number, because 3865 - 21 = 3863 is a prime.
It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.
It is a Duffinian number.
3865 is a lucky number.
It is a plaindrome in base 15.
It is a nialpdrome in base 8.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (3863) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (7) of ones.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 382 + ... + 391.
It is an arithmetic number, because the mean of its divisors is an integer number (1161).
It is an amenable number.
3865 is a deficient number, since it is larger than the sum of its proper divisors (779).
3865 is an equidigital number, since it uses as much as digits as its factorization.
3865 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 778.
The product of its digits is 720, while the sum is 22.
The square root of 3865 is about 62.1691241695.
The cubic root of 3865 is about 15.6933803080.
It can be divided in two parts, 3 and 865, that added together give a palindrome (868).
The spelling of 3865 in words is "three thousand, eight hundred sixty-five".