1216497378818 has 18 divisors (see below), whose sum is σ = 1835418388041. Its totient is φ = 604711829304.

The previous prime is 1216497378793. The next prime is 1216497378821. The reversal of 1216497378818 is 8188737946121.

It can be written as a sum of positive squares in 2 ways, for example, as 645086867929 + 571410510889 = 803173^2 + 755917^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=779903.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 279203096 + ... + 279207452.

Almost surely, 2^{1216497378818} is an apocalyptic number.

1216497378818 is a deficient number, since it is larger than the sum of its proper divisors (618921009223).

1216497378818 is an frugal number, since it uses more digits than its factorization.

1216497378818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9074 (or 4538 counting only the distinct ones).

The product of its digits is 32514048, while the sum is 65.

The spelling of 1216497378818 in words is "one trillion, two hundred sixteen billion, four hundred ninety-seven million, three hundred seventy-eight thousand, eight hundred eighteen".