321375721 has 2 divisors, whose sum is σ = 321375722. Its totient is φ = 321375720.

The previous prime is 321375697. The next prime is 321375731. The reversal of 321375721 is 127573123.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 219365721 + 102010000 = 14811^2 + 10100^2 .

It is an emirp because it is prime and its reverse (127573123) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 321375721 - 2⁵ = 321375689 is a prime.

It is not a weakly prime, because it can be changed into another prime (321375731) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160687860 + 160687861.

It is an arithmetic number, because the mean of its divisors is an integer number (160687861).

Almost surely, 2^321375721 is an apocalyptic number.

It is an amenable number.

321375721 is a deficient number, since it is larger than the sum of its proper divisors (1).

321375721 is an equidigital number, since it uses as much as digits as its factorization.

321375721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8820, while the sum is 31.

The square root of 321375721 is about 17926.9551513914. The cubic root of 321375721 is about 684.9691647902.

The spelling of 321375721 in words is "three hundred twenty-one million, three hundred seventy-five thousand, seven hundred twenty-one".