331781 has 2 divisors, whose sum is σ = 331782. Its totient is φ = 331780.

The previous prime is 331777. The next prime is 331801. The reversal of 331781 is 187133.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 330625 + 1156 = 575^2 + 34^2 .

It is an emirp because it is prime and its reverse (187133) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 331781 - 2² = 331777 is a prime.

It is a super-2 number, since 2×331781² = 220157263922, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 331781.

It is not a weakly prime, because it can be changed into another prime (331711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 165890 + 165891.

It is an arithmetic number, because the mean of its divisors is an integer number (165891).

2³³¹⁷⁸¹ is an apocalyptic number.

It is an amenable number.

331781 is a deficient number, since it is larger than the sum of its proper divisors (1).

331781 is an equidigital number, since it uses as much as digits as its factorization.

331781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 504, while the sum is 23.

The square root of 331781 is about 576.0043402614. The cubic root of 331781 is about 69.2283271377.

The spelling of 331781 in words is "three hundred thirty-one thousand, seven hundred eighty-one".