643666619 has 2 divisors, whose sum is σ = 643666620. Its totient is φ = 643666618.

The previous prime is 643666579. The next prime is 643666651. The reversal of 643666619 is 916666346.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 643666619 - 2¹⁶ = 643601083 is a prime.

It is a super-2 number, since 2×643666619² = 828613432829782322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (643666669) 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, 321833309 + 321833310.

It is an arithmetic number, because the mean of its divisors is an integer number (321833310).

Almost surely, 2^643666619 is an apocalyptic number.

643666619 is a deficient number, since it is larger than the sum of its proper divisors (1).

643666619 is an equidigital number, since it uses as much as digits as its factorization.

643666619 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 839808, while the sum is 47.

The square root of 643666619 is about 25370.5857047093. The cubic root of 643666619 is about 863.4164704635.

The spelling of 643666619 in words is "six hundred forty-three million, six hundred sixty-six thousand, six hundred nineteen".