12118561665 has 48 divisors (see below), whose sum is σ = 23742515520. Its totient is φ = 5248333440.

The previous prime is 12118561649. The next prime is 12118561667. The reversal of 12118561665 is 56616581121.

It is a happy number.

It is not a de Polignac number, because 12118561665 - 2⁴ = 12118561649 is a prime.

It is not an unprimeable number, because it can be changed into a prime (12118561667) 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, 419926 + ... + 447855.

It is an arithmetic number, because the mean of its divisors is an integer number (494635740).

Almost surely, 2^12118561665 is an apocalyptic number.

12118561665 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

12118561665 is a deficient number, since it is larger than the sum of its proper divisors (11623953855).

12118561665 is a wasteful number, since it uses less digits than its factorization.

12118561665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 867822 (or 867815 counting only the distinct ones).

The product of its digits is 86400, while the sum is 42.

The spelling of 12118561665 in words is "twelve billion, one hundred eighteen million, five hundred sixty-one thousand, six hundred sixty-five".