668409 has 12 divisors (see below), whose sum is σ = 1036944. Its totient is φ = 381864.

The previous prime is 668407. The next prime is 668417. The reversal of 668409 is 904866.

It is not a de Polignac number, because 668409 - 2¹ = 668407 is a prime.

668409 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 668409.

It is not an unprimeable number, because it can be changed into a prime (668407) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2127 + ... + 2420.

It is an arithmetic number, because the mean of its divisors is an integer number (86412).

2⁶⁶⁸⁴⁰⁹ is an apocalyptic number.

It is an amenable number.

668409 is a deficient number, since it is larger than the sum of its proper divisors (368535).

668409 is a wasteful number, since it uses less digits than its factorization.

668409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4564 (or 4557 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 33.

The square root of 668409 is about 817.5628416214. The cubic root of 668409 is about 87.4340836891.

The spelling of 668409 in words is "six hundred sixty-eight thousand, four hundred nine".