428209 has 4 divisors (see below), whose sum is σ = 429604. Its totient is φ = 426816.

The previous prime is 428177. The next prime is 428221. The reversal of 428209 is 902824.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 183184 + 245025 = 428^2 + 495^2 .

It is a cyclic number.

It is not a de Polignac number, because 428209 - 2⁵ = 428177 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (428249) 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, 12 + ... + 925.

It is an arithmetic number, because the mean of its divisors is an integer number (107401).

2⁴²⁸²⁰⁹ is an apocalyptic number.

It is an amenable number.

428209 is a deficient number, since it is larger than the sum of its proper divisors (1395).

428209 is an equidigital number, since it uses as much as digits as its factorization.

428209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1394.

The product of its (nonzero) digits is 1152, while the sum is 25.

The square root of 428209 is about 654.3768027673. The cubic root of 428209 is about 75.3734851785.

The spelling of 428209 in words is "four hundred twenty-eight thousand, two hundred nine".