205561200121031 has 2 divisors, whose sum is σ = 205561200121032. Its totient is φ = 205561200121030.

The previous prime is 205561200121009. The next prime is 205561200121061. The reversal of 205561200121031 is 130121002165502.

205561200121031 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 205561200121031 - 2¹⁸ = 205561199858887 is a prime.

It is a super-2 number, since 2×205561200121031² (a number of 29 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 205561200120985 and 205561200121003.

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, 102780600060515 + 102780600060516.

It is an arithmetic number, because the mean of its divisors is an integer number (102780600060516).

Almost surely, 2^{205561200121031} is an apocalyptic number.

205561200121031 is a deficient number, since it is larger than the sum of its proper divisors (1).

205561200121031 is an equidigital number, since it uses as much as digits as its factorization.

205561200121031 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3600, while the sum is 29.

Adding to 205561200121031 its reverse (130121002165502), we get a palindrome (335682202286533).

The spelling of 205561200121031 in words is "two hundred five trillion, five hundred sixty-one billion, two hundred million, one hundred twenty-one thousand, thirty-one".