664321 has 4 divisors (see below), whose sum is σ = 759232. Its totient is φ = 569412.

The previous prime is 664319. The next prime is 664331. The reversal of 664321 is 123466.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 664321 - 2¹ = 664319 is a prime.

It is a Duffinian number.

It is a plaindrome in base 9.

It is a nialpdrome in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 664292 and 664301.

It is not an unprimeable number, because it can be changed into a prime (664331) 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, 47445 + ... + 47458.

It is an arithmetic number, because the mean of its divisors is an integer number (189808).

2⁶⁶⁴³²¹ is an apocalyptic number.

It is an amenable number.

664321 is a deficient number, since it is larger than the sum of its proper divisors (94911).

664321 is an equidigital number, since it uses as much as digits as its factorization.

664321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94910.

The product of its digits is 864, while the sum is 22.

The square root of 664321 is about 815.0588935776. The cubic root of 664321 is about 87.2554696450.

Adding to 664321 its reverse (123466), we get a palindrome (787787).

The spelling of 664321 in words is "six hundred sixty-four thousand, three hundred twenty-one".