1666686803 has 2 divisors, whose sum is σ = 1666686804. Its totient is φ = 1666686802.

The previous prime is 1666686739. The next prime is 1666686809. The reversal of 1666686803 is 3086866661.

It is a strong prime.

It is an emirp because it is prime and its reverse (3086866661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1666686803 - 2⁶ = 1666686739 is a prime.

It is not a weakly prime, because it can be changed into another prime (1666686809) 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, 833343401 + 833343402.

It is an arithmetic number, because the mean of its divisors is an integer number (833343402).

Almost surely, 2^1666686803 is an apocalyptic number.

1666686803 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666686803 is an equidigital number, since it uses as much as digits as its factorization.

1666686803 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1492992, while the sum is 50.

The square root of 1666686803 is about 40825.0756643512. The cubic root of 1666686803 is about 1185.6358763301.

The spelling of 1666686803 in words is "one billion, six hundred sixty-six million, six hundred eighty-six thousand, eight hundred three".