3945665 has 4 divisors (see below), whose sum is σ = 4734804. Its totient is φ = 3156528.

The previous prime is 3945661. The next prime is 3945671. The reversal of 3945665 is 5665493.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5665493 = 109 ⋅51977.

It can be written as a sum of positive squares in 2 ways, for example, as 1607824 + 2337841 = 1268^2 + 1529^2 .

It is a cyclic number.

It is not a de Polignac number, because 3945665 - 2² = 3945661 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3945661) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 394562 + ... + 394571.

It is an arithmetic number, because the mean of its divisors is an integer number (1183701).

Almost surely, 2^3945665 is an apocalyptic number.

It is an amenable number.

3945665 is a deficient number, since it is larger than the sum of its proper divisors (789139).

3945665 is an equidigital number, since it uses as much as digits as its factorization.

3945665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 789138.

The product of its digits is 97200, while the sum is 38.

The square root of 3945665 is about 1986.3698044423. The cubic root of 3945665 is about 158.0180639498.

The spelling of 3945665 in words is "three million, nine hundred forty-five thousand, six hundred sixty-five".