205145521 has 16 divisors (see below), whose sum is σ = 237635200. Its totient is φ = 173467008.

The previous prime is 205145519. The next prime is 205145543. The reversal of 205145521 is 125541502.

It is a cyclic number.

It is not a de Polignac number, because 205145521 - 2¹ = 205145519 is a prime.

It is a super-2 number, since 2×205145521² = 84169369572722882, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (205145021) 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 15 ways as a sum of consecutive naturals, for example, 238390 + ... + 239248.

It is an arithmetic number, because the mean of its divisors is an integer number (14852200).

Almost surely, 2^205145521 is an apocalyptic number.

It is an amenable number.

205145521 is a deficient number, since it is larger than the sum of its proper divisors (32489679).

205145521 is a wasteful number, since it uses less digits than its factorization.

205145521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1288.

The product of its (nonzero) digits is 2000, while the sum is 25.

The square root of 205145521 is about 14322.9019755076. The cubic root of 205145521 is about 589.7763405818.

The spelling of 205145521 in words is "two hundred five million, one hundred forty-five thousand, five hundred twenty-one".