205540221 has 8 divisors (see below), whose sum is σ = 275065984. Its totient is φ = 136520640.

The previous prime is 205540207. The next prime is 205540267. The reversal of 205540221 is 122045502.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 205540221 - 2⁵ = 205540189 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 (205540921) 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 7 ways as a sum of consecutive naturals, for example, 125596 + ... + 127221.

It is an arithmetic number, because the mean of its divisors is an integer number (34383248).

Almost surely, 2^205540221 is an apocalyptic number.

It is an amenable number.

205540221 is a deficient number, since it is larger than the sum of its proper divisors (69525763).

205540221 is a wasteful number, since it uses less digits than its factorization.

205540221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 253091.

The product of its (nonzero) digits is 800, while the sum is 21.

The square root of 205540221 is about 14336.6739866679. The cubic root of 205540221 is about 590.1543415040.

Adding to 205540221 its reverse (122045502), we get a palindrome (327585723).

It can be divided in two parts, 205540 and 221, that added together give a triangular number (205761 = T₆₄₁).

The spelling of 205540221 in words is "two hundred five million, five hundred forty thousand, two hundred twenty-one".