205312521 has 4 divisors (see below), whose sum is σ = 273750032. Its totient is φ = 136875012.

The previous prime is 205312517. The next prime is 205312571. The reversal of 205312521 is 125213502.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 205312521 - 2² = 205312517 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (205312571) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 34218751 + ... + 34218756.

It is an arithmetic number, because the mean of its divisors is an integer number (68437508).

Almost surely, 2^205312521 is an apocalyptic number.

It is an amenable number.

205312521 is a deficient number, since it is larger than the sum of its proper divisors (68437511).

205312521 is an equidigital number, since it uses as much as digits as its factorization.

205312521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68437510.

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

The square root of 205312521 is about 14328.7306137006. The cubic root of 205312521 is about 589.9363342199.

The spelling of 205312521 in words is "two hundred five million, three hundred twelve thousand, five hundred twenty-one".