842509 has 4 divisors (see below), whose sum is σ = 863100. Its totient is φ = 821920.

The previous prime is 842507. The next prime is 842519. The reversal of 842509 is 905248.

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 455625 + 386884 = 675^2 + 622^2 .

It is a cyclic number.

It is not a de Polignac number, because 842509 - 2¹ = 842507 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (842507) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10234 + ... + 10315.

It is an arithmetic number, because the mean of its divisors is an integer number (215775).

2⁸⁴²⁵⁰⁹ is an apocalyptic number.

It is an amenable number.

842509 is a deficient number, since it is larger than the sum of its proper divisors (20591).

842509 is a wasteful number, since it uses less digits than its factorization.

842509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20590.

The product of its (nonzero) digits is 2880, while the sum is 28.

The square root of 842509 is about 917.8828901336. The cubic root of 842509 is about 94.4477282467.

The spelling of 842509 in words is "eight hundred forty-two thousand, five hundred nine".