643502 has 4 divisors (see below), whose sum is σ = 965256. Its totient is φ = 321750.

The previous prime is 643493. The next prime is 643507. The reversal of 643502 is 205346.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 205346 = 2 ⋅102673.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643507) by changing a digit.

643502 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160874 + ... + 160877.

It is an arithmetic number, because the mean of its divisors is an integer number (241314).

2⁶⁴³⁵⁰² is an apocalyptic number.

643502 is a deficient number, since it is larger than the sum of its proper divisors (321754).

643502 is a wasteful number, since it uses less digits than its factorization.

643502 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 321753.

The product of its (nonzero) digits is 720, while the sum is 20.

The square root of 643502 is about 802.1857640223. The cubic root of 643502 is about 86.3342857369.

Adding to 643502 its reverse (205346), we get a palindrome (848848).

The spelling of 643502 in words is "six hundred forty-three thousand, five hundred two".