663838521 has 8 divisors (see below), whose sum is σ = 885297504. Its totient is φ = 442469280.

The previous prime is 663838499. The next prime is 663838523. The reversal of 663838521 is 125838366.

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

It is not a de Polignac number, because 663838521 - 2⁷ = 663838393 is a prime.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (663838523) 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, 2691 + ... + 36536.

It is an arithmetic number, because the mean of its divisors is an integer number (110662188).

Almost surely, 2^663838521 is an apocalyptic number.

It is an amenable number.

663838521 is a deficient number, since it is larger than the sum of its proper divisors (221458983).

663838521 is a wasteful number, since it uses less digits than its factorization.

663838521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44871.

The product of its digits is 207360, while the sum is 42.

The square root of 663838521 is about 25765.0639626608. The cubic root of 663838521 is about 872.3434073916.

The spelling of 663838521 in words is "six hundred sixty-three million, eight hundred thirty-eight thousand, five hundred twenty-one".