321840 has 80 divisors (see below), whose sum is σ = 1116000. Its totient is φ = 85248.

The previous prime is 321833. The next prime is 321847. The reversal of 321840 is 48123.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (321833) and next prime (321847).

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 321840.

It is not an unprimeable number, because it can be changed into a prime (321847) by changing a digit.

321840 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2086 + ... + 2234.

It is an arithmetic number, because the mean of its divisors is an integer number (13950).

2³²¹⁸⁴⁰ is an apocalyptic number.

321840 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 321840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (558000).

321840 is an abundant number, since it is smaller than the sum of its proper divisors (794160).

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

321840 is a wasteful number, since it uses less digits than its factorization.

321840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 171 (or 159 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 321840 is about 567.3094393715. The cubic root of 321840 is about 68.5298855511.

Adding to 321840 its reverse (48123), we get a palindrome (369963).

The spelling of 321840 in words is "three hundred twenty-one thousand, eight hundred forty".