205009109 has 4 divisors (see below), whose sum is σ = 205038816. Its totient is φ = 204979404.

The previous prime is 205009099. The next prime is 205009121. The reversal of 205009109 is 901900502.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 901900502 = 2 ⋅450950251.

It is a cyclic number.

It is not a de Polignac number, because 205009109 - 2¹² = 205005013 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205009009) 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, 1502 + ... + 20304.

It is an arithmetic number, because the mean of its divisors is an integer number (51259704).

Almost surely, 2^205009109 is an apocalyptic number.

It is an amenable number.

205009109 is a deficient number, since it is larger than the sum of its proper divisors (29707).

205009109 is a wasteful number, since it uses less digits than its factorization.

205009109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29706.

The product of its (nonzero) digits is 810, while the sum is 26.

The square root of 205009109 is about 14318.1391598210. The cubic root of 205009109 is about 589.6455872044.

The spelling of 205009109 in words is "two hundred five million, nine thousand, one hundred nine".