205009511 has 16 divisors (see below), whose sum is σ = 258868224. Its totient is φ = 158193024.

The previous prime is 205009457. The next prime is 205009523. The reversal of 205009511 is 115900502.

It is a de Polignac number, because none of the positive numbers 2^k-205009511 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205009531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 34715 + ... + 40188.

It is an arithmetic number, because the mean of its divisors is an integer number (16179264).

Almost surely, 2^205009511 is an apocalyptic number.

205009511 is a deficient number, since it is larger than the sum of its proper divisors (53858713).

205009511 is a wasteful number, since it uses less digits than its factorization.

205009511 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 74950.

The product of its (nonzero) digits is 450, while the sum is 23.

The square root of 205009511 is about 14318.1531979512. The cubic root of 205009511 is about 589.6459726139.

The spelling of 205009511 in words is "two hundred five million, nine thousand, five hundred eleven".