643540 has 24 divisors (see below), whose sum is σ = 1411200. Its totient is φ = 246048.

The previous prime is 643523. The next prime is 643547. The reversal of 643540 is 45346.

643540 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643547) 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, 240 + ... + 1159.

It is an arithmetic number, because the mean of its divisors is an integer number (58800).

2⁶⁴³⁵⁴⁰ is an apocalyptic number.

It is an amenable number.

643540 is an abundant number, since it is smaller than the sum of its proper divisors (767660).

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

643540 is a wasteful number, since it uses less digits than its factorization.

643540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1431 (or 1429 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 22.

The square root of 643540 is about 802.2094489596. The cubic root of 643540 is about 86.3359851040.

Adding to 643540 its reverse (45346), we get a palindrome (688886).

The spelling of 643540 in words is "six hundred forty-three thousand, five hundred forty".