205415291561 has 2 divisors, whose sum is σ = 205415291562. Its totient is φ = 205415291560.

The previous prime is 205415291551. The next prime is 205415291581. The reversal of 205415291561 is 165192514502.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 189905079961 + 15510211600 = 435781^2 + 124540^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-205415291561 is a prime.

It is not a weakly prime, because it can be changed into another prime (205415291551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102707645780 + 102707645781.

It is an arithmetic number, because the mean of its divisors is an integer number (102707645781).

Almost surely, 2^205415291561 is an apocalyptic number.

It is an amenable number.

205415291561 is a deficient number, since it is larger than the sum of its proper divisors (1).

205415291561 is an equidigital number, since it uses as much as digits as its factorization.

205415291561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 108000, while the sum is 41.

The spelling of 205415291561 in words is "two hundred five billion, four hundred fifteen million, two hundred ninety-one thousand, five hundred sixty-one".