643520 has 28 divisors (see below), whose sum is σ = 1533144. Its totient is φ = 257280.

The previous prime is 643507. The next prime is 643523. The reversal of 643520 is 25346.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 643492 and 643501.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643523) 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, 686 + ... + 1325.

2⁶⁴³⁵²⁰ is an apocalyptic number.

It is an amenable number.

643520 is an abundant number, since it is smaller than the sum of its proper divisors (889624).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

643520 is a wasteful number, since it uses less digits than its factorization.

643520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2028 (or 2018 counting only the distinct ones).

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

The square root of 643520 is about 802.1969832903. The cubic root of 643520 is about 86.3350907086.

Adding to 643520 its reverse (25346), we get a palindrome (668866).

The spelling of 643520 in words is "six hundred forty-three thousand, five hundred twenty".