320781221 has 2 divisors, whose sum is σ = 320781222. Its totient is φ = 320781220.

The previous prime is 320781217. The next prime is 320781233. The reversal of 320781221 is 122187023.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 199120321 + 121660900 = 14111^2 + 11030^2 .

It is a cyclic number.

It is not a de Polignac number, because 320781221 - 2² = 320781217 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (320781821) 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, 160390610 + 160390611.

It is an arithmetic number, because the mean of its divisors is an integer number (160390611).

Almost surely, 2^320781221 is an apocalyptic number.

It is an amenable number.

320781221 is a deficient number, since it is larger than the sum of its proper divisors (1).

320781221 is an equidigital number, since it uses as much as digits as its factorization.

320781221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1344, while the sum is 26.

The square root of 320781221 is about 17910.3662999951. The cubic root of 320781221 is about 684.5465384617.

The spelling of 320781221 in words is "three hundred twenty million, seven hundred eighty-one thousand, two hundred twenty-one".