663231521 has 8 divisors (see below), whose sum is σ = 666674280. Its totient is φ = 659797888.

The previous prime is 663231497. The next prime is 663231529. The reversal of 663231521 is 125132366.

It can be written as a sum of positive squares in 4 ways, for example, as 6027025 + 657204496 = 2455^2 + 25636^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-663231521 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (663231529) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 178535 + ... + 182211.

It is an arithmetic number, because the mean of its divisors is an integer number (83334285).

Almost surely, 2^663231521 is an apocalyptic number.

It is an amenable number.

663231521 is a deficient number, since it is larger than the sum of its proper divisors (3442759).

663231521 is a wasteful number, since it uses less digits than its factorization.

663231521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4563.

The product of its digits is 6480, while the sum is 29.

The square root of 663231521 is about 25753.2817520408. The cubic root of 663231521 is about 872.0774421479.

Adding to 663231521 its reverse (125132366), we get a palindrome (788363887).

The spelling of 663231521 in words is "six hundred sixty-three million, two hundred thirty-one thousand, five hundred twenty-one".