643759 has 4 divisors (see below), whose sum is σ = 657504. Its totient is φ = 630016.

The previous prime is 643751. The next prime is 643781. The reversal of 643759 is 957346.

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

It is a cyclic number.

It is not a de Polignac number, because 643759 - 2³ = 643751 is a prime.

It is a Duffinian number.

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 3 ways as a sum of consecutive naturals, for example, 6802 + ... + 6895.

It is an arithmetic number, because the mean of its divisors is an integer number (164376).

2⁶⁴³⁷⁵⁹ is an apocalyptic number.

643759 is a deficient number, since it is larger than the sum of its proper divisors (13745).

643759 is a wasteful number, since it uses less digits than its factorization.

643759 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13744.

The product of its digits is 22680, while the sum is 34.

The square root of 643759 is about 802.3459353670. The cubic root of 643759 is about 86.3457775211.

The spelling of 643759 in words is "six hundred forty-three thousand, seven hundred fifty-nine".