205649761 has 4 divisors (see below), whose sum is σ = 206532612. Its totient is φ = 204766912.

The previous prime is 205649729. The next prime is 205649767. The reversal of 205649761 is 167946502.

205649761 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 40398736 + 165251025 = 6356^2 + 12855^2 .

It is a cyclic number.

It is not a de Polignac number, because 205649761 - 2⁵ = 205649729 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (205649767) 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, 441076 + ... + 441541.

It is an arithmetic number, because the mean of its divisors is an integer number (51633153).

Almost surely, 2^205649761 is an apocalyptic number.

It is an amenable number.

205649761 is a deficient number, since it is larger than the sum of its proper divisors (882851).

205649761 is an equidigital number, since it uses as much as digits as its factorization.

205649761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 882850.

The product of its (nonzero) digits is 90720, while the sum is 40.

The square root of 205649761 is about 14340.4937502166. The cubic root of 205649761 is about 590.2591612576.

The spelling of 205649761 in words is "two hundred five million, six hundred forty-nine thousand, seven hundred sixty-one".