643777055 has 4 divisors (see below), whose sum is σ = 772532472. Its totient is φ = 515021640.

The previous prime is 643777051. The next prime is 643777067. The reversal of 643777055 is 550777346.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 643777055 - 2² = 643777051 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 643776997 and 643777015.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643777051) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64377701 + ... + 64377710.

It is an arithmetic number, because the mean of its divisors is an integer number (193133118).

Almost surely, 2^643777055 is an apocalyptic number.

643777055 is a deficient number, since it is larger than the sum of its proper divisors (128755417).

643777055 is a wasteful number, since it uses less digits than its factorization.

643777055 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128755416.

The product of its (nonzero) digits is 617400, while the sum is 44.

The square root of 643777055 is about 25372.7620688013. The cubic root of 643777055 is about 863.4658473747.

The spelling of 643777055 in words is "six hundred forty-three million, seven hundred seventy-seven thousand, fifty-five".