643707671 has 2 divisors, whose sum is σ = 643707672. Its totient is φ = 643707670.

The previous prime is 643707637. The next prime is 643707677. The reversal of 643707671 is 176707346.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 643707671 - 2¹⁸ = 643445527 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643707677) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321853835 + 321853836.

It is an arithmetic number, because the mean of its divisors is an integer number (321853836).

Almost surely, 2^643707671 is an apocalyptic number.

643707671 is a deficient number, since it is larger than the sum of its proper divisors (1).

643707671 is an equidigital number, since it uses as much as digits as its factorization.

643707671 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 148176, while the sum is 41.

The square root of 643707671 is about 25371.3947389575. The cubic root of 643707671 is about 863.4348258348.

The spelling of 643707671 in words is "six hundred forty-three million, seven hundred seven thousand, six hundred seventy-one".