1321 has 2 divisors, whose sum is σ = 1322.
Its totient is φ = 1320.
The previous prime is 1319. The next prime is 1327. The reversal of 1321 is 1231.
It is a m-pointer prime, because the next prime (1327) can be obtained adding 1321 to its product of digits (6).
It is a weak prime.
It can be written as a sum of positive squares in only one way, i.e., 1296 + 25 = 36^2 + 5^2
It is an emirp because it is prime and its reverse (1231) is a distict prime.
It is a cyclic number.
It is not a de Polignac number, because 1321 - 21 = 1319 is a prime.
Together with 1319, it forms a pair of twin primes.
It is a nialpdrome in base 11 and base 12.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (1327) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (5) of ones.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 660 + 661.
It is an arithmetic number, because the mean of its divisors is an integer number (661).
21321 is an apocalyptic number.
It is an amenable number.
1321 is a deficient number, since it is larger than the sum of its proper divisors (1).
1321 is an equidigital number, since it uses as much as digits as its factorization.
1321 is an odious number, because the sum of its binary digits is odd.
The product of its digits is 6, while the sum is 7.
The square root of 1321 is about 36.3455636908.
The cubic root of 1321 is about 10.9723825100.
The spelling of 1321 in words is "one thousand, three hundred twenty-one", and is thus an iban number.