664321609 has 4 divisors (see below), whose sum is σ = 759224704. Its totient is φ = 569418516.

The previous prime is 664321607. The next prime is 664321639. The reversal of 664321609 is 906123466.

It is a happy number.

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 664321609 - 2¹ = 664321607 is a prime.

It is not an unprimeable number, because it can be changed into a prime (664321601) 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, 47451537 + ... + 47451550.

It is an arithmetic number, because the mean of its divisors is an integer number (189806176).

Almost surely, 2^664321609 is an apocalyptic number.

It is an amenable number.

664321609 is a deficient number, since it is larger than the sum of its proper divisors (94903095).

664321609 is an equidigital number, since it uses as much as digits as its factorization.

664321609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94903094.

The product of its (nonzero) digits is 46656, while the sum is 37.

The square root of 664321609 is about 25774.4371228549. The cubic root of 664321609 is about 872.5549630813.

The spelling of 664321609 in words is "six hundred sixty-four million, three hundred twenty-one thousand, six hundred nine".