643475977 has 2 divisors, whose sum is σ = 643475978. Its totient is φ = 643475976.

The previous prime is 643475957. The next prime is 643475999. The reversal of 643475977 is 779574346.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 366952336 + 276523641 = 19156^2 + 16629^2 .

It is a cyclic number.

It is not a de Polignac number, because 643475977 - 2⁷ = 643475849 is a prime.

It is a super-2 number, since 2×643475977² = 828122665952209058, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (643475927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321737988 + 321737989.

It is an arithmetic number, because the mean of its divisors is an integer number (321737989).

Almost surely, 2^643475977 is an apocalyptic number.

It is an amenable number.

643475977 is a deficient number, since it is larger than the sum of its proper divisors (1).

643475977 is an equidigital number, since it uses as much as digits as its factorization.

643475977 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4445280, while the sum is 52.

The square root of 643475977 is about 25366.8282802561. The cubic root of 643475977 is about 863.3312194492.

The spelling of 643475977 in words is "six hundred forty-three million, four hundred seventy-five thousand, nine hundred seventy-seven".