320666981 has 4 divisors (see below), whose sum is σ = 321527052. Its totient is φ = 319806912.

The previous prime is 320666977. The next prime is 320666987. The reversal of 320666981 is 189666023.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 149842081 + 170824900 = 12241^2 + 13070^2 .

It is a cyclic number.

It is not a de Polignac number, because 320666981 - 2² = 320666977 is a prime.

It is a super-2 number, since 2×320666981² = 205654625407308722, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (320666987) 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 in 3 ways as a sum of consecutive naturals, for example, 429476 + ... + 430221.

It is an arithmetic number, because the mean of its divisors is an integer number (80381763).

Almost surely, 2^320666981 is an apocalyptic number.

It is an amenable number.

320666981 is a deficient number, since it is larger than the sum of its proper divisors (860071).

320666981 is an equidigital number, since it uses as much as digits as its factorization.

320666981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 860070.

The product of its (nonzero) digits is 93312, while the sum is 41.

The square root of 320666981 is about 17907.1768014950. The cubic root of 320666981 is about 684.4652661627.

The spelling of 320666981 in words is "three hundred twenty million, six hundred sixty-six thousand, nine hundred eighty-one".