1666661020543 has 2 divisors, whose sum is σ = 1666661020544. Its totient is φ = 1666661020542.

The previous prime is 1666661020511. The next prime is 1666661020573. The reversal of 1666661020543 is 3450201666661.

It is a happy number.

It is a strong prime.

It is an emirp because it is prime and its reverse (3450201666661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1666661020543 - 2⁵ = 1666661020511 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1666661020493 and 1666661020502.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1666661020573) 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, 833330510271 + 833330510272.

It is an arithmetic number, because the mean of its divisors is an integer number (833330510272).

Almost surely, 2^{1666661020543} is an apocalyptic number.

1666661020543 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666661020543 is an equidigital number, since it uses as much as digits as its factorization.

1666661020543 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 933120, while the sum is 46.

The spelling of 1666661020543 in words is "one trillion, six hundred sixty-six billion, six hundred sixty-one million, twenty thousand, five hundred forty-three".