320720405 has 6 divisors (see below), whose sum is σ = 384912546. Its totient is φ = 256544288.

The previous prime is 320720381. The next prime is 320720417. The reversal of 320720405 is 504027023.

It can be written as a sum of positive squares in 3 ways, for example, as 65966884 + 254753521 = 8122^2 + 15961^2 .

It is not a de Polignac number, because 320720405 - 2²⁰ = 319671829 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 36041 + ... + 44049.

It is an arithmetic number, because the mean of its divisors is an integer number (64152091).

Almost surely, 2^320720405 is an apocalyptic number.

It is an amenable number.

320720405 is a deficient number, since it is larger than the sum of its proper divisors (64192141).

320720405 is an frugal number, since it uses more digits than its factorization.

320720405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16023 (or 8014 counting only the distinct ones).

The product of its (nonzero) digits is 1680, while the sum is 23.

The square root of 320720405 is about 17908.6684317958. The cubic root of 320720405 is about 684.5032753166.

Adding to 320720405 its reverse (504027023), we get a palindrome (824747428).

The spelling of 320720405 in words is "three hundred twenty million, seven hundred twenty thousand, four hundred five".