660321 has 6 divisors (see below), whose sum is σ = 953810. Its totient is φ = 440208.

The previous prime is 660299. The next prime is 660329. The reversal of 660321 is 123066.

It is a happy number.

660321 is a `hidden beast` number, since 660 + 3 + 2 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 342225 + 318096 = 585^2 + 564^2 .

It is not a de Polignac number, because 660321 - 2¹⁹ = 136033 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 660294 and 660303.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (660329) 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, 36676 + ... + 36693.

2⁶⁶⁰³²¹ is an apocalyptic number.

It is an amenable number.

660321 is a deficient number, since it is larger than the sum of its proper divisors (293489).

660321 is a wasteful number, since it uses less digits than its factorization.

660321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73375 (or 73372 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 18.

The square root of 660321 is about 812.6013782907. The cubic root of 660321 is about 87.0799898495.

Adding to 660321 its reverse (123066), we get a palindrome (783387).

The spelling of 660321 in words is "six hundred sixty thousand, three hundred twenty-one".