643779 has 12 divisors (see below), whose sum is σ = 936936. Its totient is φ = 425952.

The previous prime is 643751. The next prime is 643781. The reversal of 643779 is 977346.

643779 is a `hidden beast` number, since 643 + 7 + 7 + 9 = 666.

643779 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 643779 - 2⁷ = 643651 is a prime.

It is not an unprimeable number, because it can be changed into a prime (643729) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1944 + ... + 2250.

It is an arithmetic number, because the mean of its divisors is an integer number (78078).

2⁶⁴³⁷⁷⁹ is an apocalyptic number.

643779 is a deficient number, since it is larger than the sum of its proper divisors (293157).

643779 is a wasteful number, since it uses less digits than its factorization.

643779 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 546 (or 543 counting only the distinct ones).

The product of its digits is 31752, while the sum is 36.

The square root of 643779 is about 802.3583987222. The cubic root of 643779 is about 86.3466716951.

The spelling of 643779 in words is "six hundred forty-three thousand, seven hundred seventy-nine".