205511231 has 2 divisors, whose sum is σ = 205511232. Its totient is φ = 205511230.

The previous prime is 205511227. The next prime is 205511269. The reversal of 205511231 is 132115502.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 205511231 - 2² = 205511227 is a prime.

It is a super-2 number, since 2×205511231² = 84469732134270722, which contains 22 as substring.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (205511221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102755615 + 102755616.

It is an arithmetic number, because the mean of its divisors is an integer number (102755616).

Almost surely, 2^205511231 is an apocalyptic number.

205511231 is a deficient number, since it is larger than the sum of its proper divisors (1).

205511231 is an equidigital number, since it uses as much as digits as its factorization.

205511231 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 300, while the sum is 20.

The square root of 205511231 is about 14335.6629075882. The cubic root of 205511231 is about 590.1265944955.

Adding to 205511231 its reverse (132115502), we get a palindrome (337626733).

The spelling of 205511231 in words is "two hundred five million, five hundred eleven thousand, two hundred thirty-one".