667728 has 30 divisors (see below), whose sum is σ = 1869114. Its totient is φ = 222528.

The previous prime is 667727. The next prime is 667741. The reversal of 667728 is 827766.

It can be written as a sum of positive squares in only one way, i.e., 501264 + 166464 = 708^2 + 408^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 667692 and 667701.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (667727) 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, 2175 + ... + 2462.

2⁶⁶⁷⁷²⁸ is an apocalyptic number.

It is an amenable number.

667728 is an abundant number, since it is smaller than the sum of its proper divisors (1201386).

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

667728 is a wasteful number, since it uses less digits than its factorization.

667728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4651 (or 4642 counting only the distinct ones).

The product of its digits is 28224, while the sum is 36.

The square root of 667728 is about 817.1462537392. The cubic root of 667728 is about 87.4043798980.

The spelling of 667728 in words is "six hundred sixty-seven thousand, seven hundred twenty-eight".