664778 has 8 divisors (see below), whose sum is σ = 1013700. Its totient is φ = 326880.

The previous prime is 664777. The next prime is 664789. The reversal of 664778 is 877466.

It can be written as a sum of positive squares in 2 ways, for example, as 494209 + 170569 = 703^2 + 413^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 664778.

It is not an unprimeable number, because it can be changed into a prime (664771) 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, 2603 + ... + 2846.

2⁶⁶⁴⁷⁷⁸ is an apocalyptic number.

664778 is a deficient number, since it is larger than the sum of its proper divisors (348922).

664778 is a wasteful number, since it uses less digits than its factorization.

664778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5512.

The product of its digits is 56448, while the sum is 38.

The square root of 664778 is about 815.3391932196. The cubic root of 664778 is about 87.2754733327.

The spelling of 664778 in words is "six hundred sixty-four thousand, seven hundred seventy-eight".