664578 has 32 divisors (see below), whose sum is σ = 1528320. Its totient is φ = 213840.

The previous prime is 664571. The next prime is 664579. The reversal of 664578 is 875466.

It is a happy number.

664578 is a `hidden beast` number, since 6 + 645 + 7 + 8 = 666.

It is not an unprimeable number, because it can be changed into a prime (664571) by changing a digit.

664578 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1476 + ... + 1872.

It is an arithmetic number, because the mean of its divisors is an integer number (47760).

2⁶⁶⁴⁵⁷⁸ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 664578, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (764160).

664578 is an abundant number, since it is smaller than the sum of its proper divisors (863742).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

664578 is a wasteful number, since it uses less digits than its factorization.

664578 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 439 (or 433 counting only the distinct ones).

The product of its digits is 40320, while the sum is 36.

The square root of 664578 is about 815.2165356517. The cubic root of 664578 is about 87.2667201121.

The spelling of 664578 in words is "six hundred sixty-four thousand, five hundred seventy-eight".