205109667409 has 4 divisors (see below), whose sum is σ = 206606818404. Its totient is φ = 203612516416.

The previous prime is 205109667349. The next prime is 205109667449. The reversal of 205109667409 is 904766901502.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 904766901502 = 2 ⋅452383450751.

It can be written as a sum of positive squares in 2 ways, for example, as 62214327184 + 142895340225 = 249428^2 + 378015^2 .

It is a cyclic number.

It is not a de Polignac number, because 205109667409 - 2⁹ = 205109666897 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (205109667449) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 748575292 + ... + 748575565.

It is an arithmetic number, because the mean of its divisors is an integer number (51651704601).

Almost surely, 2^205109667409 is an apocalyptic number.

It is an amenable number.

205109667409 is a deficient number, since it is larger than the sum of its proper divisors (1497150995).

205109667409 is a wasteful number, since it uses less digits than its factorization.

205109667409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1497150994.

The product of its (nonzero) digits is 816480, while the sum is 49.

The spelling of 205109667409 in words is "two hundred five billion, one hundred nine million, six hundred sixty-seven thousand, four hundred nine".