78321 has 4 divisors (see below), whose sum is σ = 104432. Its totient is φ = 52212.

The previous prime is 78317. The next prime is 78341. The reversal of 78321 is 12387.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12387 = 3 ⋅4129.

It is not a de Polignac number, because 78321 - 2² = 78317 is a prime.

It is a super-2 number, since 2×78321² = 12268358082, which contains 22 as substring.

It is a D-number.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

78321 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (78301) 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, 13051 + ... + 13056.

It is an arithmetic number, because the mean of its divisors is an integer number (26108).

2⁷⁸³²¹ is an apocalyptic number.

It is an amenable number.

78321 is a deficient number, since it is larger than the sum of its proper divisors (26111).

78321 is a wasteful number, since it uses less digits than its factorization.

78321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26110.

The product of its digits is 336, while the sum is 21.

The square root of 78321 is about 279.8588930157. The cubic root of 78321 is about 42.7851187092.

The spelling of 78321 in words is "seventy-eight thousand, three hundred twenty-one".