205241617309 has 2 divisors, whose sum is σ = 205241617310. Its totient is φ = 205241617308.

The previous prime is 205241617267. The next prime is 205241617319. The reversal of 205241617309 is 903716142502.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 174519240025 + 30722377284 = 417755^2 + 175278^2 .

It is a cyclic number.

It is not a de Polignac number, because 205241617309 - 2⁷ = 205241617181 is a prime.

It is a super-2 number, since 2×205241617309² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (205241617319) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102620808654 + 102620808655.

It is an arithmetic number, because the mean of its divisors is an integer number (102620808655).

Almost surely, 2^205241617309 is an apocalyptic number.

It is an amenable number.

205241617309 is a deficient number, since it is larger than the sum of its proper divisors (1).

205241617309 is an equidigital number, since it uses as much as digits as its factorization.

205241617309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 90720, while the sum is 40.

The spelling of 205241617309 in words is "two hundred five billion, two hundred forty-one million, six hundred seventeen thousand, three hundred nine".