643779412877 has 2 divisors, whose sum is σ = 643779412878. Its totient is φ = 643779412876.

The previous prime is 643779412847. The next prime is 643779412883. The reversal of 643779412877 is 778214977346.

643779412877 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 606738176356 + 37041236521 = 778934^2 + 192461^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-643779412877 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643779412847) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321889706438 + 321889706439.

It is an arithmetic number, because the mean of its divisors is an integer number (321889706439).

Almost surely, 2^643779412877 is an apocalyptic number.

It is an amenable number.

643779412877 is a deficient number, since it is larger than the sum of its proper divisors (1).

643779412877 is an equidigital number, since it uses as much as digits as its factorization.

643779412877 is an evil number, because the sum of its binary digits is even.

The product of its digits is 99574272, while the sum is 65.

The spelling of 643779412877 in words is "six hundred forty-three billion, seven hundred seventy-nine million, four hundred twelve thousand, eight hundred seventy-seven".