398509 has 2 divisors, whose sum is σ = 398510. Its totient is φ = 398508.

The previous prime is 398491. The next prime is 398539. The reversal of 398509 is 905893.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 272484 + 126025 = 522^2 + 355^2 .

It is a cyclic number.

It is not a de Polignac number, because 398509 - 2⁵ = 398477 is a prime.

398509 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (398539) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 199254 + 199255.

It is an arithmetic number, because the mean of its divisors is an integer number (199255).

2³⁹⁸⁵⁰⁹ is an apocalyptic number.

It is an amenable number.

398509 is a deficient number, since it is larger than the sum of its proper divisors (1).

398509 is an equidigital number, since it uses as much as digits as its factorization.

398509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9720, while the sum is 34.

The square root of 398509 is about 631.2756925464. The cubic root of 398509 is about 73.5889678053.

The spelling of 398509 in words is "three hundred ninety-eight thousand, five hundred nine".