643433977 has 2 divisors, whose sum is σ = 643433978. Its totient is φ = 643433976.

The previous prime is 643433941. The next prime is 643434017. The reversal of 643433977 is 779334346.

643433977 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 593604496 + 49829481 = 24364^2 + 7059^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-643433977 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (643433477) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321716988 + 321716989.

It is an arithmetic number, because the mean of its divisors is an integer number (321716989).

Almost surely, 2^643433977 is an apocalyptic number.

It is an amenable number.

643433977 is a deficient number, since it is larger than the sum of its proper divisors (1).

643433977 is an equidigital number, since it uses as much as digits as its factorization.

643433977 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1143072, while the sum is 46.

The square root of 643433977 is about 25366.0004139399. Note that the first 3 decimals coincide. The cubic root of 643433977 is about 863.3124356866.

The spelling of 643433977 in words is "six hundred forty-three million, four hundred thirty-three thousand, nine hundred seventy-seven".