205311421 has 24 divisors (see below), whose sum is σ = 244906200. Its totient is φ = 171561600.

The previous prime is 205311401. The next prime is 205311433. The reversal of 205311421 is 124113502.

It can be written as a sum of positive squares in 4 ways, for example, as 9703225 + 195608196 = 3115^2 + 13986^2 .

It is not a de Polignac number, because 205311421 - 2⁹ = 205310909 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205311401) 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 23 ways as a sum of consecutive naturals, for example, 445131 + ... + 445591.

It is an arithmetic number, because the mean of its divisors is an integer number (10204425).

Almost surely, 2^205311421 is an apocalyptic number.

It is an amenable number.

205311421 is a deficient number, since it is larger than the sum of its proper divisors (39594779).

205311421 is a wasteful number, since it uses less digits than its factorization.

205311421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 685 (or 678 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 205311421 is about 14328.6922292301. The cubic root of 205311421 is about 589.9352806535.

Adding to 205311421 its reverse (124113502), we get a palindrome (329424923).

It can be divided in two parts, 20531 and 1421, that added together give a cube (21952 = 28³).

The spelling of 205311421 in words is "two hundred five million, three hundred eleven thousand, four hundred twenty-one".