265516661 has 4 divisors (see below), whose sum is σ = 265818924. Its totient is φ = 265214400.

The previous prime is 265516651. The next prime is 265516687. The reversal of 265516661 is 166615562.

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 157979761 + 107536900 = 12569^2 + 10370^2 .

It is a cyclic number.

It is not a de Polignac number, because 265516661 - 2²² = 261322357 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (265516631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 149810 + ... + 151571.

It is an arithmetic number, because the mean of its divisors is an integer number (66454731).

Almost surely, 2^265516661 is an apocalyptic number.

It is an amenable number.

265516661 is a deficient number, since it is larger than the sum of its proper divisors (302263).

265516661 is an equidigital number, since it uses as much as digits as its factorization.

265516661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 302262.

The product of its digits is 64800, while the sum is 38.

The square root of 265516661 is about 16294.6819852368. The cubic root of 265516661 is about 642.7329912464.

The spelling of 265516661 in words is "two hundred sixty-five million, five hundred sixteen thousand, six hundred sixty-one".