3965 has 8 divisors (see below), whose sum is σ = 5208. Its totient is φ = 2880.

The previous prime is 3947. The next prime is 3967. The reversal of 3965 is 5693.

It can be written as a sum of positive squares in 4 ways, for example, as 121 + 3844 = 11^2 + 62^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 3965 - 2⁸ = 3709 is a prime.

It is a Duffinian number.

3965 is an undulating number in base 8.

It is a self number, because there is not a number n which added to its sum of digits gives 3965.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3967) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35 + ... + 95.

It is an arithmetic number, because the mean of its divisors is an integer number (651).

2³⁹⁶⁵ is an apocalyptic number.

It is an amenable number.

3965 is a deficient number, since it is larger than the sum of its proper divisors (1243).

3965 is a wasteful number, since it uses less digits than its factorization.

3965 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79.

The product of its digits is 810, while the sum is 23.

The square root of 3965 is about 62.9682459657. The cubic root of 3965 is about 15.8275756227.

Subtracting 3965 from its reverse (5693), we obtain a cube (1728 = 12³).

The spelling of 3965 in words is "three thousand, nine hundred sixty-five".