643538 has 16 divisors (see below), whose sum is σ = 1129920. Its totient is φ = 269136.

The previous prime is 643523. The next prime is 643547. The reversal of 643538 is 835346.

643538 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an Ulam number.

It is a self number, because there is not a number n which added to its sum of digits gives 643538.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 68 + ... + 1136.

It is an arithmetic number, because the mean of its divisors is an integer number (70620).

2⁶⁴³⁵³⁸ is an apocalyptic number.

643538 is a deficient number, since it is larger than the sum of its proper divisors (486382).

643538 is a wasteful number, since it uses less digits than its factorization.

643538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1121.

The product of its digits is 8640, while the sum is 29.

The square root of 643538 is about 802.2082024013. The cubic root of 643538 is about 86.3358956653.

The spelling of 643538 in words is "six hundred forty-three thousand, five hundred thirty-eight".