320891681 has 4 divisors (see below), whose sum is σ = 350063664. Its totient is φ = 291719700.

The previous prime is 320891657. The next prime is 320891687. The reversal of 320891681 is 186198023.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-320891681 is a prime.

It is a super-2 number, since 2×320891681² = 205942941870011522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (320891687) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14585975 + ... + 14585996.

It is an arithmetic number, because the mean of its divisors is an integer number (87515916).

Almost surely, 2^320891681 is an apocalyptic number.

It is an amenable number.

320891681 is a deficient number, since it is larger than the sum of its proper divisors (29171983).

320891681 is a wasteful number, since it uses less digits than its factorization.

320891681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29171982.

The product of its (nonzero) digits is 20736, while the sum is 38.

The square root of 320891681 is about 17913.4497236015. The cubic root of 320891681 is about 684.6251032571.

The spelling of 320891681 in words is "three hundred twenty million, eight hundred ninety-one thousand, six hundred eighty-one".