1216326666917 has 4 divisors (see below), whose sum is σ = 1216357822860. Its totient is φ = 1216295510976.

The previous prime is 1216326666899. The next prime is 1216326666953. The reversal of 1216326666917 is 7196666236121.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 931454684161 + 284871982756 = 965119^2 + 533734^2 .

It is a cyclic number.

It is not a de Polignac number, because 1216326666917 - 2⁸ = 1216326666661 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1216326660917) 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, 15519338 + ... + 15597515.

It is an arithmetic number, because the mean of its divisors is an integer number (304089455715).

Almost surely, 2^{1216326666917} is an apocalyptic number.

It is an amenable number.

1216326666917 is a deficient number, since it is larger than the sum of its proper divisors (31155943).

1216326666917 is an equidigital number, since it uses as much as digits as its factorization.

1216326666917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31155942.

The product of its digits is 5878656, while the sum is 56.

The spelling of 1216326666917 in words is "one trillion, two hundred sixteen billion, three hundred twenty-six million, six hundred sixty-six thousand, nine hundred seventeen".