663553521 has 6 divisors (see below), whose sum is σ = 958466210. Its totient is φ = 442369008.

The previous prime is 663553483. The next prime is 663553529. The reversal of 663553521 is 125355366.

663553521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 411887025 + 251666496 = 20295^2 + 15864^2 .

It is not a de Polignac number, because 663553521 - 2¹⁰ = 663552497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (663553529) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 36864076 + ... + 36864093.

Almost surely, 2^663553521 is an apocalyptic number.

It is an amenable number.

663553521 is a deficient number, since it is larger than the sum of its proper divisors (294912689).

663553521 is a wasteful number, since it uses less digits than its factorization.

663553521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73728175 (or 73728172 counting only the distinct ones).

The product of its digits is 81000, while the sum is 36.

The square root of 663553521 is about 25759.5326238657. The cubic root of 663553521 is about 872.2185509942.

The spelling of 663553521 in words is "six hundred sixty-three million, five hundred fifty-three thousand, five hundred twenty-one".