1666680997 has 2 divisors, whose sum is σ = 1666680998. Its totient is φ = 1666680996.

The previous prime is 1666680973. The next prime is 1666681001. The reversal of 1666680997 is 7990866661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1220035041 + 446645956 = 34929^2 + 21134^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1666680997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1666680907) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 833340498 + 833340499.

It is an arithmetic number, because the mean of its divisors is an integer number (833340499).

Almost surely, 2^1666680997 is an apocalyptic number.

It is an amenable number.

1666680997 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666680997 is an equidigital number, since it uses as much as digits as its factorization.

1666680997 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5878656, while the sum is 58.

The square root of 1666680997 is about 40825.0045560316. The cubic root of 1666680997 is about 1185.6344995847.

The spelling of 1666680997 in words is "one billion, six hundred sixty-six million, six hundred eighty thousand, nine hundred ninety-seven".