678209 has 6 divisors (see below), whose sum is σ = 788994. Its totient is φ = 581280.

The previous prime is 678203. The next prime is 678211. The reversal of 678209 is 902876.

It can be written as a sum of positive squares in only one way, i.e., 529984 + 148225 = 728^2 + 385^2 .

It is not a de Polignac number, because 678209 - 2⁸ = 677953 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 (678203) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 6872 + ... + 6969.

It is an arithmetic number, because the mean of its divisors is an integer number (131499).

2⁶⁷⁸²⁰⁹ is an apocalyptic number.

It is an amenable number.

678209 is a deficient number, since it is larger than the sum of its proper divisors (110785).

678209 is a wasteful number, since it uses less digits than its factorization.

678209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13855 (or 13848 counting only the distinct ones).

The product of its (nonzero) digits is 6048, while the sum is 32.

The square root of 678209 is about 823.5344558669. The cubic root of 678209 is about 87.8593224077.

The spelling of 678209 in words is "six hundred seventy-eight thousand, two hundred nine".