42181009 has 4 divisors (see below), whose sum is σ = 45425716. Its totient is φ = 38936304.

The previous prime is 42181001. The next prime is 42181019. The reversal of 42181009 is 90018124.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 23232400 + 18948609 = 4820^2 + 4353^2 .

It is a cyclic number.

It is not a de Polignac number, because 42181009 - 2³ = 42181001 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (42181001) 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, 1622334 + ... + 1622359.

It is an arithmetic number, because the mean of its divisors is an integer number (11356429).

Almost surely, 2^42181009 is an apocalyptic number.

It is an amenable number.

42181009 is a deficient number, since it is larger than the sum of its proper divisors (3244707).

42181009 is a wasteful number, since it uses less digits than its factorization.

42181009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3244706.

The product of its (nonzero) digits is 576, while the sum is 25.

The square root of 42181009 is about 6494.6908317487. The cubic root of 42181009 is about 348.1013076478.

The spelling of 42181009 in words is "forty-two million, one hundred eighty-one thousand, nine".