399209 has 4 divisors (see below), whose sum is σ = 420240. Its totient is φ = 378180.

The previous prime is 399197. The next prime is 399221. The reversal of 399209 is 902993.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (399197) and next prime (399221).

It is a cyclic number.

It is not a de Polignac number, because 399209 - 2¹² = 395113 is a prime.

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 399209.

It is not an unprimeable number, because it can be changed into a prime (399239) 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, 10487 + ... + 10524.

It is an arithmetic number, because the mean of its divisors is an integer number (105060).

2³⁹⁹²⁰⁹ is an apocalyptic number.

It is an amenable number.

399209 is a deficient number, since it is larger than the sum of its proper divisors (21031).

399209 is a wasteful number, since it uses less digits than its factorization.

399209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21030.

The product of its (nonzero) digits is 4374, while the sum is 32.

The square root of 399209 is about 631.8298821677. The cubic root of 399209 is about 73.6320301080.

The spelling of 399209 in words is "three hundred ninety-nine thousand, two hundred nine".