320686661 has 6 divisors (see below), whose sum is σ = 331366086. Its totient is φ = 310341000.

The previous prime is 320686651. The next prime is 320686673. The reversal of 320686661 is 166686023.

It can be written as a sum of positive squares in only one way, i.e., 316626436 + 4060225 = 17794^2 + 2015^2 .

It is not a de Polignac number, because 320686661 - 2²² = 316492357 is a prime.

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 (320686651) 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 in 5 ways as a sum of consecutive naturals, for example, 165890 + ... + 167811.

It is an arithmetic number, because the mean of its divisors is an integer number (55227681).

Almost surely, 2^320686661 is an apocalyptic number.

320686661 is a gapful number since it is divisible by the number (31) formed by its first and last digit.

It is an amenable number.

320686661 is a deficient number, since it is larger than the sum of its proper divisors (10679425).

320686661 is an equidigital number, since it uses as much as digits as its factorization.

320686661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 333763 (or 333732 counting only the distinct ones).

The product of its (nonzero) digits is 62208, while the sum is 38.

The square root of 320686661 is about 17907.7262934187. The cubic root of 320686661 is about 684.4792682289.

The spelling of 320686661 in words is "three hundred twenty million, six hundred eighty-six thousand, six hundred sixty-one".