42009 has 16 divisors (see below), whose sum is σ = 65280. Its totient is φ = 23760.

The previous prime is 41999. The next prime is 42013. The reversal of 42009 is 90024.

It is not a de Polignac number, because 42009 - 2¹⁵ = 9241 is a prime.

42009 is a Rhonda number in base 6.

42009 is a lucky number.

It is a plaindrome in base 14.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 42009.

It is not an unprimeable number, because it can be changed into a prime (42019) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 594 + ... + 660.

It is an arithmetic number, because the mean of its divisors is an integer number (4080).

2⁴²⁰⁰⁹ is an apocalyptic number.

It is an amenable number.

42009 is a deficient number, since it is larger than the sum of its proper divisors (23271).

42009 is a wasteful number, since it uses less digits than its factorization.

42009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 100.

The product of its (nonzero) digits is 72, while the sum is 15.

The square root of 42009 is about 204.9609718947. The cubic root of 42009 is about 34.7627491477.

Adding to 42009 its sum of digits (15), we get a palindrome (42024).

The spelling of 42009 in words is "forty-two thousand, nine".