205215224521561 has 2 divisors, whose sum is σ = 205215224521562. Its totient is φ = 205215224521560.

The previous prime is 205215224521487. The next prime is 205215224521589. The reversal of 205215224521561 is 165125422512502.

205215224521561 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., 200899866427225 + 4315358094336 = 14173915^2 + 2077344^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-205215224521561 is a prime.

It is a super-2 number, since 2×205215224521561² (a number of 29 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (205215224521591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102607612260780 + 102607612260781.

It is an arithmetic number, because the mean of its divisors is an integer number (102607612260781).

Almost surely, 2^{205215224521561} is an apocalyptic number.

It is an amenable number.

205215224521561 is a deficient number, since it is larger than the sum of its proper divisors (1).

205215224521561 is an equidigital number, since it uses as much as digits as its factorization.

205215224521561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 480000, while the sum is 43.

The spelling of 205215224521561 in words is "two hundred five trillion, two hundred fifteen billion, two hundred twenty-four million, five hundred twenty-one thousand, five hundred sixty-one".