1216841978917 has 2 divisors, whose sum is σ = 1216841978918. Its totient is φ = 1216841978916.

The previous prime is 1216841978797. The next prime is 1216841978971. The reversal of 1216841978917 is 7198791486121.

Together with next prime (1216841978971) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 637699670721 + 579142308196 = 798561^2 + 761014^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1216841978917 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1216841978017) by changing a digit.

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 as a sum of consecutive naturals, namely, 608420989458 + 608420989459.

It is an arithmetic number, because the mean of its divisors is an integer number (608420989459).

Almost surely, 2^{1216841978917} is an apocalyptic number.

It is an amenable number.

1216841978917 is a deficient number, since it is larger than the sum of its proper divisors (1).

1216841978917 is an equidigital number, since it uses as much as digits as its factorization.

1216841978917 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12192768, while the sum is 64.

The spelling of 1216841978917 in words is "one trillion, two hundred sixteen billion, eight hundred forty-one million, nine hundred seventy-eight thousand, nine hundred seventeen".