11761666561 has 16 divisors (see below), whose sum is σ = 12935842560. Its totient is φ = 10657366720.

The previous prime is 11761666549. The next prime is 11761666571. The reversal of 11761666561 is 16566616711.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-11761666561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11761666541) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 131005 + ... + 201706.

It is an arithmetic number, because the mean of its divisors is an integer number (808490160).

Almost surely, 2^11761666561 is an apocalyptic number.

It is an amenable number.

11761666561 is a deficient number, since it is larger than the sum of its proper divisors (1174175999).

11761666561 is a wasteful number, since it uses less digits than its factorization.

11761666561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 332816.

The product of its digits is 272160, while the sum is 46.

The spelling of 11761666561 in words is "eleven billion, seven hundred sixty-one million, six hundred sixty-six thousand, five hundred sixty-one".