643045649 has 2 divisors, whose sum is σ = 643045650. Its totient is φ = 643045648.

The previous prime is 643045619. The next prime is 643045657. The reversal of 643045649 is 946540346.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 607129600 + 35916049 = 24640^2 + 5993^2 .

It is a cyclic number.

It is not a de Polignac number, because 643045649 - 2²⁸ = 374610193 is a prime.

It is not a weakly prime, because it can be changed into another prime (643045619) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321522824 + 321522825.

It is an arithmetic number, because the mean of its divisors is an integer number (321522825).

Almost surely, 2^643045649 is an apocalyptic number.

It is an amenable number.

643045649 is a deficient number, since it is larger than the sum of its proper divisors (1).

643045649 is an equidigital number, since it uses as much as digits as its factorization.

643045649 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 311040, while the sum is 41.

The square root of 643045649 is about 25358.3447606503. The cubic root of 643045649 is about 863.1387240758.

The spelling of 643045649 in words is "six hundred forty-three million, forty-five thousand, six hundred forty-nine".