201561 has 4 divisors (see below), whose sum is σ = 268752. Its totient is φ = 134372.

The previous prime is 201557. The next prime is 201577. The reversal of 201561 is 165102.

201561 is nontrivially palindromic in base 12.

201561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

201561 is an esthetic number in base 12, because in such base its adjacent digits differ by 1.

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.

It is a cyclic number.

It is not a de Polignac number, because 201561 - 2² = 201557 is a prime.

It is a D-number.

It is a self number, because there is not a number n which added to its sum of digits gives 201561.

It is not an unprimeable number, because it can be changed into a prime (201511) 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, 33591 + ... + 33596.

It is an arithmetic number, because the mean of its divisors is an integer number (67188).

2²⁰¹⁵⁶¹ is an apocalyptic number.

It is an amenable number.

201561 is a deficient number, since it is larger than the sum of its proper divisors (67191).

201561 is an equidigital number, since it uses as much as digits as its factorization.

201561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67190.

The product of its (nonzero) digits is 60, while the sum is 15.

The square root of 201561 is about 448.9554543605. The cubic root of 201561 is about 58.6321070272.

Adding to 201561 its reverse (165102), we get a palindrome (366663).

The spelling of 201561 in words is "two hundred one thousand, five hundred sixty-one".