1668640769 has 2 divisors, whose sum is σ = 1668640770. Its totient is φ = 1668640768.

The previous prime is 1668640741. The next prime is 1668640783. The reversal of 1668640769 is 9670468661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1358880769 + 309760000 = 36863^2 + 17600^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1668640769 is a prime.

It is a super-2 number, since 2×1668640769² = 5568724031937822722, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1668640769.

It is not a weakly prime, because it can be changed into another prime (1668640469) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 834320384 + 834320385.

It is an arithmetic number, because the mean of its divisors is an integer number (834320385).

Almost surely, 2^1668640769 is an apocalyptic number.

It is an amenable number.

1668640769 is a deficient number, since it is larger than the sum of its proper divisors (1).

1668640769 is an equidigital number, since it uses as much as digits as its factorization.

1668640769 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2612736, while the sum is 53.

The square root of 1668640769 is about 40848.9996083135. Note that the first 3 decimals coincide. The cubic root of 1668640769 is about 1186.0990282230.

The spelling of 1668640769 in words is "one billion, six hundred sixty-eight million, six hundred forty thousand, seven hundred sixty-nine".