12991097666 has 8 divisors (see below), whose sum is σ = 19753587084. Its totient is φ = 6406568640.

The previous prime is 12991097663. The next prime is 12991097671. The reversal of 12991097666 is 66679019921.

It can be written as a sum of positive squares in 2 ways, for example, as 12200307025 + 790790641 = 110455^2 + 28121^2 .

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

It is not an unprimeable number, because it can be changed into a prime (12991097663) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 44489915 + ... + 44490206.

Almost surely, 2^12991097666 is an apocalyptic number.

12991097666 is a deficient number, since it is larger than the sum of its proper divisors (6762489418).

12991097666 is an equidigital number, since it uses as much as digits as its factorization.

12991097666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88980196.

The product of its (nonzero) digits is 2204496, while the sum is 56.

The spelling of 12991097666 in words is "twelve billion, nine hundred ninety-one million, ninety-seven thousand, six hundred sixty-six".