678409 has 2 divisors, whose sum is σ = 678410. Its totient is φ = 678408.

The previous prime is 678407. The next prime is 678413. The reversal of 678409 is 904876.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 455625 + 222784 = 675^2 + 472^2 .

It is a cyclic number.

It is not a de Polignac number, because 678409 - 2¹ = 678407 is a prime.

Together with 678407, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (678401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 339204 + 339205.

It is an arithmetic number, because the mean of its divisors is an integer number (339205).

2⁶⁷⁸⁴⁰⁹ is an apocalyptic number.

It is an amenable number.

678409 is a deficient number, since it is larger than the sum of its proper divisors (1).

678409 is an equidigital number, since it uses as much as digits as its factorization.

678409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12096, while the sum is 34.

The square root of 678409 is about 823.6558747438. The cubic root of 678409 is about 87.8679579647.

The spelling of 678409 in words is "six hundred seventy-eight thousand, four hundred nine".