663561 has 12 divisors (see below), whose sum is σ = 1015092. Its totient is φ = 416256.

The previous prime is 663557. The next prime is 663563. The reversal of 663561 is 165366.

It can be written as a sum of positive squares in 2 ways, for example, as 207936 + 455625 = 456^2 + 675^2 .

It is not a de Polignac number, because 663561 - 2² = 663557 is a prime.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 663561.

It is not an unprimeable number, because it can be changed into a prime (663563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2016 + ... + 2321.

It is an arithmetic number, because the mean of its divisors is an integer number (84591).

2⁶⁶³⁵⁶¹ is an apocalyptic number.

It is an amenable number.

663561 is a deficient number, since it is larger than the sum of its proper divisors (351531).

663561 is a wasteful number, since it uses less digits than its factorization.

663561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4360 (or 4357 counting only the distinct ones).

The product of its digits is 3240, while the sum is 27.

The square root of 663561 is about 814.5925361799. The cubic root of 663561 is about 87.2221827946. Note that the first 3 decimals are identical.

The spelling of 663561 in words is "six hundred sixty-three thousand, five hundred sixty-one".