816321 has 16 divisors (see below), whose sum is σ = 1229760. Its totient is φ = 477120.

The previous prime is 816317. The next prime is 816329. The reversal of 816321 is 123618.

It is not a de Polignac number, because 816321 - 2² = 816317 is a prime.

It is an Ulam number.

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

It is not an unprimeable number, because it can be changed into a prime (816329) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 531 + ... + 1383.

It is an arithmetic number, because the mean of its divisors is an integer number (76860).

2⁸¹⁶³²¹ is an apocalyptic number.

It is an amenable number.

816321 is a deficient number, since it is larger than the sum of its proper divisors (413439).

816321 is a wasteful number, since it uses less digits than its factorization.

816321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 896.

The product of its digits is 288, while the sum is 21.

The square root of 816321 is about 903.5048422670. The cubic root of 816321 is about 93.4588263718.

Adding to 816321 its reverse (123618), we get a palindrome (939939).

The spelling of 816321 in words is "eight hundred sixteen thousand, three hundred twenty-one".