7981321 has 2 divisors, whose sum is σ = 7981322. Its totient is φ = 7981320.

The previous prime is 7981319. The next prime is 7981327. The reversal of 7981321 is 1231897.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6431296 + 1550025 = 2536^2 + 1245^2 .

It is a cyclic number.

It is not a de Polignac number, because 7981321 - 2¹ = 7981319 is a prime.

Together with 7981319, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (7981327) 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, 3990660 + 3990661.

It is an arithmetic number, because the mean of its divisors is an integer number (3990661).

Almost surely, 2^7981321 is an apocalyptic number.

It is an amenable number.

7981321 is a deficient number, since it is larger than the sum of its proper divisors (1).

7981321 is an equidigital number, since it uses as much as digits as its factorization.

7981321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3024, while the sum is 31.

The square root of 7981321 is about 2825.1231831550. The cubic root of 7981321 is about 199.8442203617.

The spelling of 7981321 in words is "seven million, nine hundred eighty-one thousand, three hundred twenty-one".