4005639 has 16 divisors (see below), whose sum is σ = 6474240. Its totient is φ = 2427480.

The previous prime is 4005619. The next prime is 4005643. The reversal of 4005639 is 9365004.

It is a happy number.

It is a de Polignac number, because none of the positive numbers 2^k-4005639 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

4005639 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (4005619) 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 15 ways as a sum of consecutive naturals, for example, 6447 + ... + 7040.

It is an arithmetic number, because the mean of its divisors is an integer number (404640).

Almost surely, 2^4005639 is an apocalyptic number.

4005639 is a deficient number, since it is larger than the sum of its proper divisors (2468601).

4005639 is a wasteful number, since it uses less digits than its factorization.

4005639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13507 (or 13501 counting only the distinct ones).

The product of its (nonzero) digits is 3240, while the sum is 27.

The square root of 4005639 is about 2001.4092535011. The cubic root of 4005639 is about 158.8146647921.

The spelling of 4005639 in words is "four million, five thousand, six hundred thirty-nine".