643791 has 8 divisors (see below), whose sum is σ = 874800. Its totient is φ = 420992.

The previous prime is 643781. The next prime is 643847. The reversal of 643791 is 197346.

It is a happy number.

643791 is digitally balanced in base 7, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 643791 - 2¹³ = 635599 is a prime.

643791 is strictly pandigital in base 7.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643751) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1866 + ... + 2183.

It is an arithmetic number, because the mean of its divisors is an integer number (109350).

2⁶⁴³⁷⁹¹ is an apocalyptic number.

643791 is a deficient number, since it is larger than the sum of its proper divisors (231009).

643791 is a wasteful number, since it uses less digits than its factorization.

643791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4105.

The product of its digits is 4536, while the sum is 30.

The square root of 643791 is about 802.3658766423. The cubic root of 643791 is about 86.3472081906.

The spelling of 643791 in words is "six hundred forty-three thousand, seven hundred ninety-one".