561636 has 18 divisors (see below), whose sum is σ = 1419782. Its totient is φ = 187200.

The previous prime is 561607. The next prime is 561667. The reversal of 561636 is 636165.

It can be written as a sum of positive squares in only one way, i.e., 553536 + 8100 = 744^2 + 90^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is an alternating number because its digits alternate between odd and even.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 7765 + ... + 7836.

2⁵⁶¹⁶³⁶ is an apocalyptic number.

It is an amenable number.

561636 is an abundant number, since it is smaller than the sum of its proper divisors (858146).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

561636 is a wasteful number, since it uses less digits than its factorization.

561636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15611 (or 15606 counting only the distinct ones).

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

The square root of 561636 is about 749.4237786460. The cubic root of 561636 is about 82.5058948956.

Subtracting 561636 from its reverse (636165), we obtain a square (74529 = 273²).

It can be divided in two parts, 56163 and 6, that added together give a square (56169 = 237²).

The spelling of 561636 in words is "five hundred sixty-one thousand, six hundred thirty-six".