205191680 has 40 divisors (see below), whose sum is σ = 491985252. Its totient is φ = 82075648.

The previous prime is 205191631. The next prime is 205191689. The reversal of 205191680 is 86191502.

It can be written as a sum of positive squares in 2 ways, for example, as 188018944 + 17172736 = 13712^2 + 4144^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a Harshad number since it is a multiple of its sum of digits (32).

It is not an unprimeable number, because it can be changed into a prime (205191689) 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, 37517 + ... + 42636.

Almost surely, 2^205191680 is an apocalyptic number.

205191680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

205191680 is an abundant number, since it is smaller than the sum of its proper divisors (286793572).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

205191680 is an frugal number, since it uses more digits than its factorization.

205191680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80176 (or 80160 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 32.

The square root of 205191680 is about 14324.5132552558. The cubic root of 205191680 is about 589.8205716954.

The spelling of 205191680 in words is "two hundred five million, one hundred ninety-one thousand, six hundred eighty".