2661320565 has 48 divisors (see below), whose sum is σ = 4674898800. Its totient is φ = 1400426496.

The previous prime is 2661320551. The next prime is 2661320567. The reversal of 2661320565 is 5650231662.

It is a happy number.

2661320565 is a `hidden beast` number, since 2 + 6 + 61 + 32 + 0 + 565 = 666.

2661320565 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 8 ways, for example, as 4639716 + 2656680849 = 2154^2 + 51543^2 .

It is a de Polignac number, because none of the positive numbers 2^k-2661320565 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2661320567) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1318437 + ... + 1320453.

It is an arithmetic number, because the mean of its divisors is an integer number (97393725).

Almost surely, 2^2661320565 is an apocalyptic number.

It is an amenable number.

2661320565 is a deficient number, since it is larger than the sum of its proper divisors (2013578235).

2661320565 is a wasteful number, since it uses less digits than its factorization.

2661320565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2406 (or 2403 counting only the distinct ones).

The product of its (nonzero) digits is 64800, while the sum is 36.

The square root of 2661320565 is about 51587.9885729227. The cubic root of 2661320565 is about 1385.7952337688.

The spelling of 2661320565 in words is "two billion, six hundred sixty-one million, three hundred twenty thousand, five hundred sixty-five".