4009 has 4 divisors (see below), whose sum is σ = 4240.
Its totient is φ = 3780.
The previous prime is 4007. The next prime is 4013. The reversal of 4009 is 9004.
It can be divided in two parts, 400 and 9, that multiplied together give a square (3600 = 602).
It is a happy number.
It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.
It is a cyclic number.
It is not a de Polignac number, because 4009 - 21 = 4007 is a prime.
It is a Duffinian number.
4009 is a modest number, since divided by 9 gives 4 as remainder.
It is a plaindrome in base 7.
It is a nialpdrome in base 4, base 8, base 9 and base 16.
It is a self number, because there is not a number n which added to its sum of digits gives 4009.
It is not an unprimeable number, because it can be changed into a prime (4001) 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, 87 + ... + 124.
It is an arithmetic number, because the mean of its divisors is an integer number (1060).
It is an amenable number.
4009 is a deficient number, since it is larger than the sum of its proper divisors (231).
4009 is a wasteful number, since it uses less digits than its factorization.
4009 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 230.
The product of its (nonzero) digits is 36, while the sum is 13.
The square root of 4009 is about 63.3166644731.
The cubic root of 4009 is about 15.8859071096.
The spelling of 4009 in words is "four thousand, nine".