205116661 has 2 divisors, whose sum is σ = 205116662. Its totient is φ = 205116660.

The previous prime is 205116649. The next prime is 205116671. The reversal of 205116661 is 166611502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 106213636 + 98903025 = 10306^2 + 9945^2 .

It is a cyclic number.

It is not a de Polignac number, because 205116661 - 2¹³ = 205108469 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (205116631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102558330 + 102558331.

It is an arithmetic number, because the mean of its divisors is an integer number (102558331).

Almost surely, 2^205116661 is an apocalyptic number.

It is an amenable number.

205116661 is a deficient number, since it is larger than the sum of its proper divisors (1).

205116661 is an equidigital number, since it uses as much as digits as its factorization.

205116661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2160, while the sum is 28.

The square root of 205116661 is about 14321.8944626750. The cubic root of 205116661 is about 589.7486825834.

It can be divided in two parts, 20511 and 6661, that added together give a palindrome (27172).

The spelling of 205116661 in words is "two hundred five million, one hundred sixteen thousand, six hundred sixty-one".