205561200121061 has 2 divisors, whose sum is σ = 205561200121062. Its totient is φ = 205561200121060.

The previous prime is 205561200121031. The next prime is 205561200121073. The reversal of 205561200121061 is 160121002165502.

205561200121061 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 199273172452225 + 6288027668836 = 14116415^2 + 2507594^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-205561200121061 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (205561200121001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102780600060530 + 102780600060531.

It is an arithmetic number, because the mean of its divisors is an integer number (102780600060531).

Almost surely, 2^{205561200121061} is an apocalyptic number.

It is an amenable number.

205561200121061 is a deficient number, since it is larger than the sum of its proper divisors (1).

205561200121061 is an equidigital number, since it uses as much as digits as its factorization.

205561200121061 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7200, while the sum is 32.

Adding to 205561200121061 its reverse (160121002165502), we get a palindrome (365682202286563).

The spelling of 205561200121061 in words is "two hundred five trillion, five hundred sixty-one billion, two hundred million, one hundred twenty-one thousand, sixty-one".