643591 has 8 divisors (see below), whose sum is σ = 715904. Its totient is φ = 574560.

The previous prime is 643589. The next prime is 643619. The reversal of 643591 is 195346.

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

It is a cyclic number.

It is not a de Polignac number, because 643591 - 2¹ = 643589 is a prime.

It is a Duffinian number.

643591 is a lucky number.

It is a nialpdrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643691) 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, 396 + ... + 1201.

It is an arithmetic number, because the mean of its divisors is an integer number (89488).

2⁶⁴³⁵⁹¹ is an apocalyptic number.

643591 is a deficient number, since it is larger than the sum of its proper divisors (72313).

643591 is a wasteful number, since it uses less digits than its factorization.

643591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1641.

The product of its digits is 3240, while the sum is 28.

The square root of 643591 is about 802.2412355395. The cubic root of 643591 is about 86.3382657283.

It can be divided in two parts, 6435 and 91, that multiplied together give a palindrome (585585).

The spelling of 643591 in words is "six hundred forty-three thousand, five hundred ninety-one".