643777049 has 2 divisors, whose sum is σ = 643777050. Its totient is φ = 643777048.

The previous prime is 643777009. The next prime is 643777051. The reversal of 643777049 is 940777346.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 381499024 + 262278025 = 19532^2 + 16195^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-643777049 is a prime.

Together with 643777051, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 643776994 and 643777012.

It is not a weakly prime, because it can be changed into another prime (643777009) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321888524 + 321888525.

It is an arithmetic number, because the mean of its divisors is an integer number (321888525).

Almost surely, 2^643777049 is an apocalyptic number.

It is an amenable number.

643777049 is a deficient number, since it is larger than the sum of its proper divisors (1).

643777049 is an equidigital number, since it uses as much as digits as its factorization.

643777049 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 889056, while the sum is 47.

The square root of 643777049 is about 25372.7619505642. The cubic root of 643777049 is about 863.4658446922.

The spelling of 643777049 in words is "six hundred forty-three million, seven hundred seventy-seven thousand, forty-nine".