643345 has 4 divisors (see below), whose sum is σ = 772020. Its totient is φ = 514672.

The previous prime is 643303. The next prime is 643369. The reversal of 643345 is 543346.

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

It can be written as a sum of positive squares in 2 ways, for example, as 77841 + 565504 = 279^2 + 752^2 .

It is a cyclic number.

It is not a de Polignac number, because 643345 - 2⁷ = 643217 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64330 + ... + 64339.

It is an arithmetic number, because the mean of its divisors is an integer number (193005).

2⁶⁴³³⁴⁵ is an apocalyptic number.

It is an amenable number.

643345 is a deficient number, since it is larger than the sum of its proper divisors (128675).

643345 is a wasteful number, since it uses less digits than its factorization.

643345 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128674.

The product of its digits is 4320, while the sum is 25.

The square root of 643345 is about 802.0879004199. The cubic root of 643345 is about 86.3272639585.

Subtracting from 643345 its reverse (543346), we obtain a palindrome (99999).

The spelling of 643345 in words is "six hundred forty-three thousand, three hundred forty-five".