643611 has 8 divisors (see below), whose sum is σ = 872464. Its totient is φ = 421920.

The previous prime is 643589. The next prime is 643619. The reversal of 643611 is 116346.

643611 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 643611 - 2⁶ = 643547 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (643619) 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, 1576 + ... + 1941.

It is an arithmetic number, because the mean of its divisors is an integer number (109058).

2⁶⁴³⁶¹¹ is an apocalyptic number.

643611 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

643611 is a deficient number, since it is larger than the sum of its proper divisors (228853).

643611 is a wasteful number, since it uses less digits than its factorization.

643611 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3581.

The product of its digits is 432, while the sum is 21.

The square root of 643611 is about 802.2537005212. The cubic root of 643611 is about 86.3391600579.

Adding to 643611 its reverse (116346), we get a palindrome (759957).

The spelling of 643611 in words is "six hundred forty-three thousand, six hundred eleven".