643536 has 60 divisors (see below), whose sum is σ = 1861860. Its totient is φ = 207360.

The previous prime is 643523. The next prime is 643547. The reversal of 643536 is 635346.

It can be written as a sum of positive squares in 2 ways, for example, as 207936 + 435600 = 456^2 + 660^2 .

It is an Ulam number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5850 + ... + 5958.

It is an arithmetic number, because the mean of its divisors is an integer number (31031).

2⁶⁴³⁵³⁶ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 643536, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (930930).

643536 is an abundant number, since it is smaller than the sum of its proper divisors (1218324).

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

643536 is a wasteful number, since it uses less digits than its factorization.

643536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 164 (or 155 counting only the distinct ones).

The product of its digits is 6480, while the sum is 27.

The square root of 643536 is about 802.2069558412. The cubic root of 643536 is about 86.3358062264.

It can be divided in two parts, 64 and 3536, that added together give a square (3600 = 60²).

The spelling of 643536 in words is "six hundred forty-three thousand, five hundred thirty-six".