• If 3 + 7 and (+1)3 + 7 are both divisible by a number > 1, then = 331. (For example, this happens for = 320.)
It is a happy number.
331 is nontrivially palindromic in base 15.
It is a strong prime.
It is a cyclic number.
It is a de Polignac number, because none of the positive numbers 2k-331 is a prime.
331 is an undulating number in base 15.
331 is a lucky number.
It is a plaindrome in base 12, base 14 and base 16.
It is a nialpdrome in base 7 and base 10.
It is a panconsummate number.
It is a good prime.
331 is an equidigital number, since it uses as much as digits as its factorization.
331 is an odious number, because the sum of its binary digits is odd.
The square root of 331 is about 18.1934053987. The cubic root of 331 is about 6.9173964166.
Adding to 331 its reverse (133), we get a palindrome (464).
The spelling of 331 in words is "three hundred thirty-one", and thus it is an aban number.