320785921 has 2 divisors, whose sum is σ = 320785922. Its totient is φ = 320785920.

The previous prime is 320785909. The next prime is 320785939. The reversal of 320785921 is 129587023.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 225450225 + 95335696 = 15015^2 + 9764^2 .

It is a cyclic number.

It is not a de Polignac number, because 320785921 - 2⁵ = 320785889 is a prime.

It is a super-2 number, since 2×320785921² = 205807214223636482, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (320785901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160392960 + 160392961.

It is an arithmetic number, because the mean of its divisors is an integer number (160392961).

Almost surely, 2^320785921 is an apocalyptic number.

It is an amenable number.

320785921 is a deficient number, since it is larger than the sum of its proper divisors (1).

320785921 is an equidigital number, since it uses as much as digits as its factorization.

320785921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 30240, while the sum is 37.

The square root of 320785921 is about 17910.4975084446. The cubic root of 320785921 is about 684.5498817091.

The spelling of 320785921 in words is "three hundred twenty million, seven hundred eighty-five thousand, nine hundred twenty-one".