561663 has 12 divisors (see below), whose sum is σ = 859248. Its totient is φ = 352320.

The previous prime is 561607. The next prime is 561667. The reversal of 561663 is 366165.

It is not a de Polignac number, because 561663 - 2⁶ = 561599 is a prime.

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (561667) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1683 + ... + 1988.

It is an arithmetic number, because the mean of its divisors is an integer number (71604).

2⁵⁶¹⁶⁶³ is an apocalyptic number.

561663 is a deficient number, since it is larger than the sum of its proper divisors (297585).

561663 is a wasteful number, since it uses less digits than its factorization.

561663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3694 (or 3691 counting only the distinct ones).

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

The square root of 561663 is about 749.4417922694. The cubic root of 561663 is about 82.5072169995.

It can be divided in two parts, 56166 and 3, that added together give a square (56169 = 237²).

The spelling of 561663 in words is "five hundred sixty-one thousand, six hundred sixty-three".