42909 has 4 divisors (see below), whose sum is σ = 57216. Its totient is φ = 28604.

The previous prime is 42901. The next prime is 42923. The reversal of 42909 is 90924.

42909 = 65² + 66² + ... + 73².

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 42909 - 2³ = 42901 is a prime.

It is a D-number.

It is a Curzon number.

It is a plaindrome in base 14.

It is a nialpdrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (42901) 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, 7149 + ... + 7154.

It is an arithmetic number, because the mean of its divisors is an integer number (14304).

2⁴²⁹⁰⁹ is an apocalyptic number.

It is an amenable number.

42909 is a deficient number, since it is larger than the sum of its proper divisors (14307).

42909 is a wasteful number, since it uses less digits than its factorization.

42909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14306.

The product of its (nonzero) digits is 648, while the sum is 24.

The square root of 42909 is about 207.1448768374. The cubic root of 42909 is about 35.0092492562.

The spelling of 42909 in words is "forty-two thousand, nine hundred nine".