321643 has 4 divisors (see below), whose sum is σ = 367600. Its totient is φ = 275688.

The previous prime is 321631. The next prime is 321647. The reversal of 321643 is 346123.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 346123 = 19 ⋅18217.

It is not a de Polignac number, because 321643 - 2⁵ = 321611 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 321643.

It is not an unprimeable number, because it can be changed into a prime (321647) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22968 + ... + 22981.

It is an arithmetic number, because the mean of its divisors is an integer number (91900).

2³²¹⁶⁴³ is an apocalyptic number.

321643 is a deficient number, since it is larger than the sum of its proper divisors (45957).

321643 is an equidigital number, since it uses as much as digits as its factorization.

321643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45956.

The product of its digits is 432, while the sum is 19.

The square root of 321643 is about 567.1357862100. The cubic root of 321643 is about 68.5159001930.

Adding to 321643 its reverse (346123), we get a palindrome (667766).

It can be divided in two parts, 321 and 643, that multiplied together give a triangular number (206403 = T₆₄₂).

The spelling of 321643 in words is "three hundred twenty-one thousand, six hundred forty-three".