7820321 has 2 divisors, whose sum is σ = 7820322. Its totient is φ = 7820320.

The previous prime is 7820317. The next prime is 7820347. The reversal of 7820321 is 1230287.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7639696 + 180625 = 2764^2 + 425^2 .

It is a cyclic number.

It is not a de Polignac number, because 7820321 - 2² = 7820317 is a prime.

It is a super-2 number, since 2×7820321² = 122314841086082, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a nialpdrome in base 16.

It is not a weakly prime, because it can be changed into another prime (7820821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3910160 + 3910161.

It is an arithmetic number, because the mean of its divisors is an integer number (3910161).

Almost surely, 2^7820321 is an apocalyptic number.

It is an amenable number.

7820321 is a deficient number, since it is larger than the sum of its proper divisors (1).

7820321 is an equidigital number, since it uses as much as digits as its factorization.

7820321 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 672, while the sum is 23.

The square root of 7820321 is about 2796.4836849158. The cubic root of 7820321 is about 198.4913230857.

The spelling of 7820321 in words is "seven million, eight hundred twenty thousand, three hundred twenty-one".