643724171 has 2 divisors, whose sum is σ = 643724172. Its totient is φ = 643724170.

The previous prime is 643724143. The next prime is 643724183. The reversal of 643724171 is 171427346.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 643724171 - 2¹⁰ = 643723147 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (643724101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321862085 + 321862086.

It is an arithmetic number, because the mean of its divisors is an integer number (321862086).

Almost surely, 2^643724171 is an apocalyptic number.

643724171 is a deficient number, since it is larger than the sum of its proper divisors (1).

643724171 is an equidigital number, since it uses as much as digits as its factorization.

643724171 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 28224, while the sum is 35.

The square root of 643724171 is about 25371.7199062263. The cubic root of 643724171 is about 863.4422031758.

The spelling of 643724171 in words is "six hundred forty-three million, seven hundred twenty-four thousand, one hundred seventy-one".