1678748896661 has 2 divisors, whose sum is σ = 1678748896662. Its totient is φ = 1678748896660.

The previous prime is 1678748896651. The next prime is 1678748896663. The reversal of 1678748896661 is 1666988478761.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1124161870225 + 554587026436 = 1060265^2 + 744706^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1678748896661 is a prime.

Together with 1678748896663, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1678748896663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 839374448330 + 839374448331.

It is an arithmetic number, because the mean of its divisors is an integer number (839374448331).

Almost surely, 2^{1678748896661} is an apocalyptic number.

It is an amenable number.

1678748896661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1678748896661 is an equidigital number, since it uses as much as digits as its factorization.

1678748896661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1170505728, while the sum is 77.

The spelling of 1678748896661 in words is "one trillion, six hundred seventy-eight billion, seven hundred forty-eight million, eight hundred ninety-six thousand, six hundred sixty-one".