42409 has 2 divisors, whose sum is σ = 42410. Its totient is φ = 42408.

The previous prime is 42407. The next prime is 42433. The reversal of 42409 is 90424.

42409 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 38809 + 3600 = 197^2 + 60^2 .

It is a cyclic number.

It is not a de Polignac number, because 42409 - 2¹ = 42407 is a prime.

Together with 42407, it forms a pair of twin primes.

It is a nialpdrome in base 15.

It is not a weakly prime, because it can be changed into another prime (42403) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21204 + 21205.

It is an arithmetic number, because the mean of its divisors is an integer number (21205).

2⁴²⁴⁰⁹ is an apocalyptic number.

It is an amenable number.

42409 is a deficient number, since it is larger than the sum of its proper divisors (1).

42409 is an equidigital number, since it uses as much as digits as its factorization.

42409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 288, while the sum is 19.

The square root of 42409 is about 205.9344555921. The cubic root of 42409 is about 34.8727350867.

The spelling of 42409 in words is "forty-two thousand, four hundred nine".