203561 has 4 divisors (see below), whose sum is σ = 204624. Its totient is φ = 202500.

The previous prime is 203549. The next prime is 203563. The reversal of 203561 is 165302.

203561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 165302 = 2 ⋅82651.

It is a cyclic number.

It is not a de Polignac number, because 203561 - 2¹⁴ = 187177 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 12.

It is not an unprimeable number, because it can be changed into a prime (203563) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 155 + ... + 656.

It is an arithmetic number, because the mean of its divisors is an integer number (51156).

2²⁰³⁵⁶¹ is an apocalyptic number.

It is an amenable number.

203561 is a deficient number, since it is larger than the sum of its proper divisors (1063).

203561 is an equidigital number, since it uses as much as digits as its factorization.

203561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1062.

The product of its (nonzero) digits is 180, while the sum is 17.

The square root of 203561 is about 451.1773487222. The cubic root of 203561 is about 58.8253958820.

Adding to 203561 its reverse (165302), we get a palindrome (368863).

The spelling of 203561 in words is "two hundred three thousand, five hundred sixty-one".