205213521 has 32 divisors (see below), whose sum is σ = 296828928. Its totient is φ = 125737920.

The previous prime is 205213513. The next prime is 205213523. The reversal of 205213521 is 125312502.

It is not a de Polignac number, because 205213521 - 2³ = 205213513 is a prime.

It is a super-2 number, since 2×205213521² = 84225178402434882, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (205213523) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 421140 + ... + 421626.

It is an arithmetic number, because the mean of its divisors is an integer number (9275904).

Almost surely, 2^205213521 is an apocalyptic number.

It is an amenable number.

205213521 is a deficient number, since it is larger than the sum of its proper divisors (91615407).

205213521 is a wasteful number, since it uses less digits than its factorization.

205213521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 741.

The product of its (nonzero) digits is 600, while the sum is 21.

The square root of 205213521 is about 14325.2755994431. The cubic root of 205213521 is about 589.8414981677.

It can be divided in two parts, 20521 and 3521, that added together give a palindrome (24042).

The spelling of 205213521 in words is "two hundred five million, two hundred thirteen thousand, five hundred twenty-one".