664993509 has 8 divisors (see below), whose sum is σ = 888827520. Its totient is φ = 442244256.

The previous prime is 664993507. The next prime is 664993529. The reversal of 664993509 is 905399466.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 664993509 - 2¹ = 664993507 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664993507) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 269757 + ... + 272210.

It is an arithmetic number, because the mean of its divisors is an integer number (111103440).

Almost surely, 2^664993509 is an apocalyptic number.

It is an amenable number.

664993509 is a deficient number, since it is larger than the sum of its proper divisors (223834011).

664993509 is a wasteful number, since it uses less digits than its factorization.

664993509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 542379.

The product of its (nonzero) digits is 1574640, while the sum is 51.

The square root of 664993509 is about 25787.4680610563. The cubic root of 664993509 is about 872.8490335688.

The spelling of 664993509 in words is "six hundred sixty-four million, nine hundred ninety-three thousand, five hundred nine".