664501521 has 8 divisors (see below), whose sum is σ = 890952480. Its totient is φ = 440525792.

The previous prime is 664501493. The next prime is 664501531. The reversal of 664501521 is 125105466.

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

It is a cyclic number.

It is not a de Polignac number, because 664501521 - 2²⁶ = 597392657 is a prime.

It is a super-2 number, since 2×664501521² = 883124542822626882, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (664501531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 618180 + ... + 619253.

It is an arithmetic number, because the mean of its divisors is an integer number (111369060).

Almost surely, 2^664501521 is an apocalyptic number.

It is an amenable number.

664501521 is a deficient number, since it is larger than the sum of its proper divisors (226450959).

664501521 is a wasteful number, since it uses less digits than its factorization.

664501521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1237615.

The product of its (nonzero) digits is 7200, while the sum is 30.

The square root of 664501521 is about 25777.9270113017. The cubic root of 664501521 is about 872.6337246014.

Adding to 664501521 its reverse (125105466), we get a palindrome (789606987).

The spelling of 664501521 in words is "six hundred sixty-four million, five hundred one thousand, five hundred twenty-one".