643929877 has 2 divisors, whose sum is σ = 643929878. Its totient is φ = 643929876.

The previous prime is 643929829. The next prime is 643929883. The reversal of 643929877 is 778929346.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 485144676 + 158785201 = 22026^2 + 12601^2 .

It is a cyclic number.

It is not a de Polignac number, because 643929877 - 2⁷ = 643929749 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643929577) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321964938 + 321964939.

It is an arithmetic number, because the mean of its divisors is an integer number (321964939).

Almost surely, 2^643929877 is an apocalyptic number.

It is an amenable number.

643929877 is a deficient number, since it is larger than the sum of its proper divisors (1).

643929877 is an equidigital number, since it uses as much as digits as its factorization.

643929877 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4572288, while the sum is 55.

The square root of 643929877 is about 25375.7734266367. The cubic root of 643929877 is about 863.5341661281.

The spelling of 643929877 in words is "six hundred forty-three million, nine hundred twenty-nine thousand, eight hundred seventy-seven".