1668640741 has 2 divisors, whose sum is σ = 1668640742. Its totient is φ = 1668640740.

The previous prime is 1668640703. The next prime is 1668640769. The reversal of 1668640741 is 1470468661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1668395716 + 245025 = 40846^2 + 495^2 .

It is a cyclic number.

It is not a de Polignac number, because 1668640741 - 2⁷ = 1668640613 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1668643741) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 834320370 + 834320371.

It is an arithmetic number, because the mean of its divisors is an integer number (834320371).

Almost surely, 2^1668640741 is an apocalyptic number.

It is an amenable number.

1668640741 is a deficient number, since it is larger than the sum of its proper divisors (1).

1668640741 is an equidigital number, since it uses as much as digits as its factorization.

1668640741 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 193536, while the sum is 43.

The square root of 1668640741 is about 40848.9992655879. Note that the first 3 decimals coincide. The cubic root of 1668640741 is about 1186.0990215887.

The spelling of 1668640741 in words is "one billion, six hundred sixty-eight million, six hundred forty thousand, seven hundred forty-one".