3999965 has 4 divisors (see below), whose sum is σ = 4799964. Its totient is φ = 3199968.

The previous prime is 3999949. The next prime is 3999971. The reversal of 3999965 is 5699993.

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 2785561 + 1214404 = 1669^2 + 1102^2 .

It is a cyclic number.

It is not a de Polignac number, because 3999965 - 2⁴ = 3999949 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 399992 + ... + 400001.

It is an arithmetic number, because the mean of its divisors is an integer number (1199991).

Almost surely, 2^3999965 is an apocalyptic number.

It is an amenable number.

3999965 is a deficient number, since it is larger than the sum of its proper divisors (799999).

3999965 is an equidigital number, since it uses as much as digits as its factorization.

3999965 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 799998.

The product of its digits is 590490, while the sum is 50.

The square root of 3999965 is about 1999.9912499809. The cubic root of 3999965 is about 158.7396422035.

The spelling of 3999965 in words is "three million, nine hundred ninety-nine thousand, nine hundred sixty-five".