11561666565 has 32 divisors (see below), whose sum is σ = 19323277056. Its totient is φ = 5891916800.

The previous prime is 11561666549. The next prime is 11561666569. The reversal of 11561666565 is 56566616511.

It is not a de Polignac number, because 11561666565 - 2⁴ = 11561666549 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11561666569) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 319915 + ... + 354215.

It is an arithmetic number, because the mean of its divisors is an integer number (603852408).

Almost surely, 2^11561666565 is an apocalyptic number.

11561666565 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

11561666565 is a deficient number, since it is larger than the sum of its proper divisors (7761610491).

11561666565 is a wasteful number, since it uses less digits than its factorization.

11561666565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35309.

The product of its digits is 972000, while the sum is 48.

The spelling of 11561666565 in words is "eleven billion, five hundred sixty-one million, six hundred sixty-six thousand, five hundred sixty-five".