1161666615561 has 8 divisors (see below), whose sum is σ = 1598852976384. Its totient is φ = 749462332560.

The previous prime is 1161666615511. The next prime is 1161666615617. The reversal of 1161666615561 is 1655166661611.

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

It is not a de Polignac number, because 1161666615561 - 2¹⁹ = 1161666091273 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1161666615511) 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, 6245519346 + ... + 6245519531.

It is an arithmetic number, because the mean of its divisors is an integer number (199856622048).

Almost surely, 2^{1161666615561} is an apocalyptic number.

It is an amenable number.

1161666615561 is a deficient number, since it is larger than the sum of its proper divisors (437186360823).

1161666615561 is a wasteful number, since it uses less digits than its factorization.

1161666615561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12491038911.

The product of its digits is 1166400, while the sum is 51.

The spelling of 1161666615561 in words is "one trillion, one hundred sixty-one billion, six hundred sixty-six million, six hundred fifteen thousand, five hundred sixty-one".