998509 has 4 divisors (see below), whose sum is σ = 1014940. Its totient is φ = 982080.

The previous prime is 998497. The next prime is 998513. The reversal of 998509 is 905899.

998509 = T₆₂ + T₆₃ + ... + T₁₈₃.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 905899 = 109 ⋅8311.

It can be written as a sum of positive squares in 2 ways, for example, as 142884 + 855625 = 378^2 + 925^2 .

It is a cyclic number.

It is not a de Polignac number, because 998509 - 2⁷ = 998381 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (998539) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8124 + ... + 8245.

It is an arithmetic number, because the mean of its divisors is an integer number (253735).

2⁹⁹⁸⁵⁰⁹ is an apocalyptic number.

It is an amenable number.

998509 is a deficient number, since it is larger than the sum of its proper divisors (16431).

998509 is a wasteful number, since it uses less digits than its factorization.

998509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16430.

The product of its (nonzero) digits is 29160, while the sum is 40.

The square root of 998509 is about 999.2542219075. The cubic root of 998509 is about 99.9502752786.

The spelling of 998509 in words is "nine hundred ninety-eight thousand, five hundred nine".