205511243 has 6 divisors (see below), whose sum is σ = 239064156. Its totient is φ = 176152452.

The previous prime is 205511231. The next prime is 205511269. The reversal of 205511243 is 342115502.

It is not a de Polignac number, because 205511243 - 2⁴ = 205511227 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (205511443) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2097005 + ... + 2097102.

It is an arithmetic number, because the mean of its divisors is an integer number (39844026).

Almost surely, 2^205511243 is an apocalyptic number.

205511243 is a deficient number, since it is larger than the sum of its proper divisors (33552913).

205511243 is an equidigital number, since it uses as much as digits as its factorization.

205511243 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4194121 (or 4194114 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 23.

The square root of 205511243 is about 14335.6633261248. The cubic root of 205511243 is about 590.1266059815.

Adding to 205511243 its reverse (342115502), we get a palindrome (547626745).

The spelling of 205511243 in words is "two hundred five million, five hundred eleven thousand, two hundred forty-three".