3861 has 16 divisors (see below), whose sum is σ = 6720. Its totient is φ = 2160.

The previous prime is 3853. The next prime is 3863. The reversal of 3861 is 1683.

It is not a de Polignac number, because 3861 - 2³ = 3853 is a prime.

It is a Curzon number.

It is a plaindrome in base 12, base 14 and base 15.

It is a zygodrome in base 12.

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 15 ways as a sum of consecutive naturals, for example, 291 + ... + 303.

It is an arithmetic number, because the mean of its divisors is an integer number (420).

2³⁸⁶¹ is an apocalyptic number.

It is an amenable number.

3861 is a deficient number, since it is larger than the sum of its proper divisors (2859).

3861 is a wasteful number, since it uses less digits than its factorization.

3861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33 (or 27 counting only the distinct ones).

The product of its digits is 144, while the sum is 18.

The square root of 3861 is about 62.1369455316. The cubic root of 3861 is about 15.6879645953.

Adding to 3861 its product of digits (144), we get a triangular number (4005 = T₈₉).

It can be divided in two parts, 38 and 61, that added together give a palindrome (99).

The spelling of 3861 in words is "three thousand, eight hundred sixty-one".