1165505556661 has 8 divisors (see below), whose sum is σ = 1238103442400. Its totient is φ = 1094033219760.

The previous prime is 1165505556637. The next prime is 1165505556689. The reversal of 1165505556661 is 1666555055611.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1165505556661 - 2⁵ = 1165505556629 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1165505556599 and 1165505556608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1165505556601) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 281385075 + ... + 281389216.

It is an arithmetic number, because the mean of its divisors is an integer number (154762930300).

Almost surely, 2^{1165505556661} is an apocalyptic number.

It is an amenable number.

1165505556661 is a deficient number, since it is larger than the sum of its proper divisors (72597885739).

1165505556661 is a wasteful number, since it uses less digits than its factorization.

1165505556661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 562774419.

The product of its (nonzero) digits is 4050000, while the sum is 52.

The spelling of 1165505556661 in words is "one trillion, one hundred sixty-five billion, five hundred five million, five hundred fifty-six thousand, six hundred sixty-one".