3944639 has 4 divisors (see below), whose sum is σ = 3950256. Its totient is φ = 3939024.

The previous prime is 3944627. The next prime is 3944669. The reversal of 3944639 is 9364493.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 3944639 - 2²⁰ = 2896063 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3944669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1574 + ... + 3219.

It is an arithmetic number, because the mean of its divisors is an integer number (987564).

Almost surely, 2^3944639 is an apocalyptic number.

3944639 is a deficient number, since it is larger than the sum of its proper divisors (5617).

3944639 is an equidigital number, since it uses as much as digits as its factorization.

3944639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5616.

The product of its digits is 69984, while the sum is 38.

The square root of 3944639 is about 1986.1115275835. Note that the first 3 decimals coincide. The cubic root of 3944639 is about 158.0043661668.

The spelling of 3944639 in words is "three million, nine hundred forty-four thousand, six hundred thirty-nine".